JP2011032130A - Device for bleeding gas discharged from cement kiln and driving method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device for bleeding a gas discharged from a cement kiln, which can generate a uniform swirling flow. <P>SOLUTION: The device for bleeding a part of a gas discharged from a cement kiln includes: the first cylindrical bleeding tube for bleeding a part of the gas discharged from the cement kiln; one cylindrically opened or a plurality of inlet ports arranged at equal intervals in a circumference direction for introducing swirling air flow for cooling at the tube wall of the first bleeding tube; a swirl enhancement unit which surrounds the circumference of the first bleeding tube in the form of concentric circles at the position where the inlet ports are disposed and stores a plurality of swirl vanes arranged at equal intervals in the circumference direction (each swirl vane faces the tangential direction to the inner wall of the first bleeding tube or to the side outer than that direction in order to generate the swirl flow along the inner wall of the first bleeding tube after the air for cooling enters into the first bleeding tube from the inlet port for the swirl air flow for cooling); and one duct connected for flow in the approximately tangential direction to the outer wall of the swirl enhancement unit or a plurality of ducts arranged at equal intervals in the direction of a circumference for transporting the air for cooling (the number of swirl vanes is greater than the number of ducts for transporting cooling air). <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention occurs, for example, on an inner wall surface of a preheater or the like when a cement clinker is fired in a cement kiln facility such as a cement kiln facility with SP (suspension preheater) or a cement kiln facility with NSP (new suspension preheater), The present invention relates to an apparatus for extracting and treating a part of exhaust gas from a cement kiln in order to remove volatile components (alkali chloride, alkali sulfate, etc.) that cause coating from a cement kiln facility, and an operation method thereof. Here, the inner wall surface of the preheater or the like refers to a calcining furnace, the lowest cyclone of SP or NSP, and a raw material inlet of the kiln and ducts through which the kiln exhaust gas connected thereto passes.

  The exhaust gas from the cement kiln facility contains volatile components such as alkali chlorides and alkali sulfates. These volatile components are gradually concentrated while circulating between the preheater and the kiln, and are taken into the clinker to adversely affect the quality of the cement and adhere to the inner wall of the preheater as a coating. This may cause the inner wall surface to be blocked. Therefore, in order to reduce the volatile components in the cement kiln facility, exhaust gas extraction treatment called so-called chlorine bypass method or alkali bypass method has been performed. This method is a method of reducing the concentration of volatile components in the exhaust gas by extracting a part of the exhaust gas from the cement kiln with an extraction pipe.

  Cement kiln exhaust gas to be extracted is at a high temperature of 1000 ° C. or higher, and at this temperature state, volatile components will not be liquefied or solidified to cause coating in the extraction processing apparatus, but the exhaust gas will be cooled. When a volatile component having a melting point or lower than the sublimation point comes into contact with the inner wall of the extraction apparatus, the volatile component adheres to the inner wall as a coating. Therefore, in implementing the chlorine bypass method, it is desired to cool the volatile components in the exhaust gas so as not to form a coating in the extraction processing apparatus, and various techniques for this purpose have been proposed. .

For example, in Japanese Patent Laid-Open No. 9-175847 (Patent Document 1), cement kiln exhaust gas extracted by an extraction pipe is guided to a cooling chamber, and the inside of the cooling chamber wall and the leading end of the extraction pipe on the kiln bottom side is described. Cooling air connected to the cooling chamber by blowing sufficient cooling air from the outer periphery of the cooling chamber to cool the exhaust gas temperature at the outlet of the chamber to 350 ° C. or lower so that a swirling flow of cooling air is generated along the wall surface. The exhaust gas and the cooling air are gradually mixed by maintaining the swirling flow in the chamber outlet duct, and then introduced into the chamber, and the swirling flow is disturbed to mix the exhaust gas and the cooling air. Disclosed is a method for treating a bleed cement kiln exhaust gas, which is cooled to a temperature of 0 ° C. or less and removed lump and then guided to a dust collector to remove powder. (Claim 1)
In paragraph 0008 of Patent Document 1, the following (1) to (5) are disclosed.
(1) By blowing cooling air along the inner wall surface from the outer periphery of the cooling chamber and protecting the inner wall of the cooling chamber and the cooling chamber outlet duct with the swirling flow of cooling air, the generation of coating in the cooling chamber is suppressed. What you can do.
(2) When the swirl flow in the cooling chamber is strengthened, the occurrence of coating in the extraction pipe is also suppressed.
(3) By making the length and shape of the cooling chamber outlet duct appropriate, the swirling flow generated in the cooling chamber is maintained also in the cooling chamber outlet duct, and the occurrence of coating in the duct is also suppressed. thing.
(4) Gradually mixing while maintaining the swirling flow in the cooling chamber and the cooling chamber outlet duct, cooling to a predetermined temperature or lower, leading to the chamber, disturbing the swirling flow in the chamber, and mixing exhaust gas and cooling air Then, the occurrence of coating in the chamber and beyond is suppressed.
(5) The temperature of the gas after mixing is 350 ° C. or less. At this temperature, the volatile component to be removed contained in the exhaust gas is completely solidified and can be removed as a fume by a dust collector.
In paragraph 0011 of Patent Document 1, the inner wall of the bleed pipe portion is protected by an air curtain caused by the backflow of the swirling flow of cooling air blown from the fan into the cooling chamber, thereby suppressing the occurrence of coating at the location. Are listed.
In paragraph 0019 of Patent Document 1, when a plurality of cooling air inlets are provided and cooling air is blown from a plurality of locations, the swirling flow in the cooling chamber becomes uniform, and the back flow in the extraction pipe portion becomes uniform at a low wind speed. It is also described that it is effective in suppressing the occurrence of coating in the bleed pipe and cooling chamber.

  Japanese Patent Application Laid-Open No. 11-35355 (Patent Document 2) discloses that a probe having a double-pipe structure is communicated with a kiln exhaust gas flow path in order to efficiently cool the exhaust gas in the kiln bypass. In the exhaust gas cooling method in a kiln bypass in which a part of the kiln exhaust gas is extracted through the inner pipe and the cooling gas is supplied to the fluid passage between the inner pipe and the outer pipe of the probe, the cooling gas is supplied to the inner pipe. An exhaust gas cooling method in a kiln bypass is disclosed in which a mixed quenching region is formed at the tip of the probe by guiding the tip inward (Claim 1). According to the present invention, the extraction gas is rapidly cooled in the mixing and quenching region at the tip of the probe, so that alkali, chlorine, etc. in the extraction gas can be efficiently solidified and concentrated to a fine powder portion of the dust in the extraction gas. In addition, since the cooling air is guided to the inside of the tip of the inner tube, it is possible to prevent the air from flowing into the rotary kiln (paragraph 0039).

In the inventions described in Patent Document 1 and Patent Document 2, a fan for blowing cooling air into the extraction system and a fan for extraction are required, respectively, or the extraction pipe needs to have a special double structure. To do. Therefore, in Japanese Patent Laid-Open No. 2001-335348 (Patent Document 3), for the purpose of simplifying the structure of the extraction system and facilitating the adjustment during operation, the cement kiln exhaust gas is extracted from the kiln inlet hood with an extraction pipe. In addition, in the cement kiln exhaust gas extraction processing apparatus that mixes the extracted exhaust gas with cooling air to reduce the exhaust gas temperature, the extraction pipe is disposed in the tip of the suction duct having a diameter-expanding portion that gradually expands toward the tip. The outlet side end is inserted with a gap around it, and the inside of the suction duct is set to a negative pressure, and exhaust gas is extracted from the extraction pipe to the suction duct, and outside air is sucked as cooling air from the gap. There has been proposed a cement kiln exhaust gas bleeder treatment device characterized in that a bleeder suction device that flows into the suction duct is connected to the suction duct (contract). Section 1).
According to the present invention, outside air can be taken in as cooling air from the gap between the extraction pipe and the intake duct without using a fan for sending cooling air into the suction duct, and the exhaust gas generated by the outside air can be generated with a simple structure. It is assumed that cooling can be performed (paragraph 0040).

JP-A-9-175847 JP-A-11-35355 JP 2001-335348 A

  In the invention described in Patent Literature 1, the cooling air is swirled along the inner wall of the cooling chamber, thereby forming an air curtain by the cooling air swirling along the inner wall. It aims at cooling by gradually mixing with cooling air while turning, and has a certain effect in preventing coating in the cooling chamber.

  However, this cooling method still has room for improvement. Patent Document 1 describes that when a plurality of cooling air blowing ports are provided and cooling air is blown from a plurality of locations, the swirling flow in the cooling chamber becomes uniform. Since the air curtain by cooling air is stabilized by making the swirl flow uniform, the coating prevention effect is enhanced. However, if the number of air blowing ports having a structure as described in Patent Document 1 is increased, the cooling effect is increased accordingly. The air piping layout becomes complicated and expensive. It is not realistic to provide a large number of air inlets due to space constraints.

  Further, the invention described in Patent Document 1 aims to suppress the occurrence of coating on the inner wall of the extraction pipe by causing the swirling flow to flow backward from the cooling chamber toward the tip of the extraction pipe. It was found that when the air flows backward, the temperature of the gas contacting the inner wall of the extraction pipe easily falls within the range of 400 to 900 ° C. where the coating tends to be generated due to mixing with the cement kiln exhaust gas.

  On the other hand, the inventions described in Patent Document 2 and Patent Document 3 are intended to rapidly mix the extracted cement kiln exhaust gas with cooling air to cool the exhaust gas rapidly, but a uniform swirl flow is obtained. I can't. Further, in the rapid mixing process at the inlet of the extraction pipe, the extraction gas containing a volatile component that causes coating near the inner wall of the extraction pipe is in a high concentration and is in a temperature range of 400 to 900 ° C. until the mixing is completed. As such, there remains a concern for coating formation.

  Then, this invention makes it the 1st subject to provide the cement kiln waste gas extraction processing apparatus which can generate | occur | produce a uniform swirling flow, and its operating method, without requiring complicated piping management. This invention makes it the 2nd subject to provide the cement kiln exhaust gas extraction processing apparatus which can prevent the backflow of the air for cooling, and its operating method.

  The present inventor conducted extensive research to solve the above problems, and by devising the structure of the cooling air inlet, the swirl flow along the inner wall of the extraction pipe for cooling air was formed more uniformly. The air curtain that protects the inner wall of the extraction pipe from the high-temperature cement kiln exhaust gas has been found to last long in the axial direction of the extraction pipe.

That is, in one aspect, the present invention is a cement kiln exhaust gas extraction processing device that extracts a portion of cement kiln exhaust gas, mixes the extracted exhaust gas with cooling air, and processes the exhaust gas at a reduced temperature.
A cylindrical first extraction pipe for extracting a part of the cement kiln exhaust gas;
A plurality of swirling air flow inlets for cooling arranged in a cylindrical shape in the pipe wall of the first bleed pipe, or arranged at equal intervals in the circumferential direction;
A swirl strengthening unit that concentrically surrounds the first bleed pipe at the location where the swirling air flow inlet for cooling is installed, and contains a plurality of swirl vanes arranged at equal intervals in the circumferential direction, and Each swirl vane has a first swirl flow that allows cooling air to enter the first bleed pipe from the cooling swirl air flow inlet and create a swirl flow along the inner wall of the first bleed pipe. Facing the tangential direction of the inner wall of the bleed pipe or the outside of it,
One cooling air conveyance duct arranged in fluid communication in the substantially tangential direction of the outer wall of the swirl strengthening unit or a plurality of cooling air conveyance ducts arranged at equal intervals in the circumferential direction, where the number of swirl vanes is the cooling air conveyance duct More than the number of
It is a cement kiln exhaust gas extraction processing apparatus provided with.

  In one embodiment of the cement kiln exhaust gas bleeder according to the present invention, each swirl vane faces 10 to 40 degrees outside the tangential direction of the inner wall of the first bleeder pipe.

  In another embodiment of the cement kiln exhaust gas extraction apparatus according to the present invention, each swirl vane is attached at an acute angle with respect to the flow direction of the cement kiln exhaust gas flowing in the first extraction pipe.

  In still another embodiment of the cement kiln exhaust gas extraction apparatus according to the present invention, the number of cooling air conveyance ducts is two, three, or four.

  In still another embodiment of the cement kiln exhaust gas extraction apparatus according to the present invention, the number of swirling blades is 15 to 36.

  In still another embodiment of the cement kiln exhaust gas extraction apparatus according to the present invention, the swirl vane is rotatably attached so as to be able to rotate around the first extraction pipe.

  In still another embodiment of the cement kiln exhaust gas extraction apparatus according to the present invention, a cooling straight air flow inlet that is concentric with the first extraction pipe is further provided downstream of the cooling swirl air inlet. The cooling straight air flow inlet is formed by concentrically inserting the downstream end of the first extraction pipe into a second extraction pipe having a diameter larger than that of the first extraction pipe.

  In still another embodiment, the cement kiln exhaust gas extraction apparatus according to the present invention further includes a cooling air conveying pipe that defines the flow of the cooling straight air flow further downstream of the swirl strengthening unit. The pipe is larger in diameter than the first and second bleed pipes, concentrically surrounds the first and second bleed pipes, and the downstream end is opened to allow cooling air to flow in, The cooling air that has flowed in flows in the direction opposite to the flow direction of the cement kiln exhaust gas through the outer periphery of the second extraction pipe, and then reverses and cools at the inlet of the first extraction pipe and the second extraction pipe The upstream end is closed so that it can go to the straight air flow inlet.

According to another aspect of the present invention, there is provided a method for operating a cement kiln exhaust gas extraction apparatus according to the present invention, wherein the cross-sectional area of the first extraction pipe is Ae (m ² ), and the cement flows through the first extraction pipe inlet. The average flow velocity of the kiln exhaust gas is Ue (m / s), the density is ρe (kg / m ³ ), the number of cooling air conveyance ducts is N (lines), and the sectional area per cooling air conveyance duct is At. (M ² ), when the average flow velocity of cooling air at the outlet of the cooling air conveyance duct is Ut (m / s) and the density is ρt (kg / m ³ ),
(At · N · ρt · Ut ² ) / (Ae · ρe · Ue ² ) = 0.35-10
N ≧ 2
This is a method of operating the cement kiln exhaust gas bleeder apparatus under conditions that satisfy the above conditions.

In another aspect of the present invention, there is provided a method for operating a cement kiln exhaust gas bleeder according to the present invention, wherein the cross-sectional area of the first bleed pipe is Ae (m ² ) and flows through the first bleed pipe inlet. The average flow velocity of the cement kiln exhaust gas is Ue (m / s), the density is ρe (kg / m ³ ), the number of cooling air transfer ducts is N (lines), and the cross-sectional area per cooling air transfer duct is At (m ² ), the average flow velocity of cooling air at the outlet of the cooling air conveyance duct is Ut (m / s), the density is ρt (kg / m ³ ), and the cross-sectional area of the cooling straight air flow inlet is Ad ( m ² ), when the average flow velocity of cooling air at the cooling straight air flow inlet is Ud (m / s) and the density is ρd (kg / m ³ ),
(At · N · ρt · Ut ² ) / (Ae · ρe · Ue ² ) = 0.15-5
And (Ad · ρd · Ud ² ) / (Ae · ρe · Ue ² ) = 2.2 to 360
N ≧ 2
This is a method of operating the cement kiln exhaust gas bleeder apparatus under conditions that satisfy the above conditions.

  In one embodiment, the operating method according to the present invention is the first and, if present, the temperature of the mixed gas of the cooling air and the cement kiln exhaust gas contacting the inner wall of the second extraction pipe is set at the cooling swirling air flow inlet. Hold at 350 ° C. or lower downstream.

  In another embodiment of the operation method according to the present invention, the concentration of the cement kiln exhaust gas is cooled with respect to the mixed gas of the cooling air and the cement kiln exhaust gas in contact with the inner wall of the first extraction pipe and the first extraction pipe, if present. The temperature is kept below 10% by volume until the temperature of the hottest portion of the mixed gas is cooled to 350 ° C. or lower downstream of the swirling air flow inlet.

  In yet another embodiment of the operating method according to the present invention, the swirling air flow for cooling and the straight air flow for cooling if present are directly or downstream of the first and second bleed pipes if present. It is generated by making the inside of the extraction pipe negative pressure by the suction force from the exhaust suction device for the main exhaust duct of the cement kiln equipment connected indirectly.

  According to the present invention, in order to remove the volatile components such as alkali chloride and alkali sulfate contained in the cement kiln exhaust gas, in order to remove a part of the cement kiln exhaust gas with an extraction pipe, A uniform swirling flow can be easily generated. In a preferred embodiment of the present invention, it is possible to prevent the cooling air from flowing back through the extraction pipe.

It is an example of 1 composition of cement kiln equipment provided with the cement kiln exhaust gas extraction processing device concerning the present invention. It is the figure which looked at 1st embodiment of the cement kiln waste gas extraction processing apparatus which concerns on this invention from the front direction orthogonal to the central axis of an extraction pipe. It is the figure which looked at 1st embodiment of the cement kiln waste gas extraction processing apparatus which concerns on this invention from the center axis direction of the extraction pipe. It is the figure which looked at 2nd embodiment of the cement kiln exhaust gas extraction processing apparatus which concerns on this invention from the front direction orthogonal to the central axis of an extraction pipe. It is the figure which looked at the example of the cement kiln exhaust gas extraction processing apparatus for a comparison from the front direction orthogonal to the central axis of an extraction pipe. It is the figure which looked at the example of the cement kiln exhaust gas extraction processing apparatus for a comparison from the central axis direction of the extraction pipe. Example No. as seen from the front direction perpendicular to the central axis of the bleed tube. Fig. 4-4 isotherm diagram. Example No. as seen from the front direction perpendicular to the central axis of the bleed tube. FIG. 4 is an isodensity map of 4-4.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

<1. Cement kiln equipment>
FIG. 1 shows a configuration example of a cement kiln facility provided with a cement kiln exhaust gas extraction apparatus 101 according to the present invention. Exhaust gas containing volatile components discharged from the rotary kiln 102 mainly includes a kiln inlet hood 104 which is a bent portion of a duct connecting the pre-heater 103 and the rotary kiln, a rising duct 105 extending immediately above the kiln inlet hood 104, preheating A calcination furnace 106 for calcination of the cement raw material and a cyclone 107 are sequentially passed along a dotted line in the figure, and are directed to an exhaust suction device 108 such as a kiln IDF fan. After exiting the exhaust suction device, the exhaust is exhausted from the chimney through the dryer 109, the stabilizer 110, and the electrostatic precipitator 111.

  A cement kiln exhaust gas extraction port 112 can be provided on any wall surface of the kiln inlet hood 104, the rising duct 105, and the calcining furnace 106. A first extraction pipe 113 constituting a part of the cement kiln exhaust gas treatment extraction apparatus is connected to the extraction port 112, and a part of the cement kiln exhaust gas is extracted through this. Since the volatile component that causes the generation of the coating is in a temperature range where it is easy to concentrate in the kiln exhaust gas, it is preferable to bleed from the wall surfaces of the kiln inlet hood 104 and the rising duct 105. The first extraction pipe 113 is preferably attached to the wall surface on the cement kiln side (the wall surface on the right side in the figure) for the reason that the flow rate of the kiln exhaust gas is relatively slower than the main flow.

<2. First Embodiment of Cement Kiln Exhaust Gas Extraction Processing Device>
Next, a first embodiment of the cement kiln exhaust gas extraction apparatus according to the present invention will be described with reference to FIGS. 2-1 and 2-2. The cement kiln exhaust gas flowing into the first extraction pipe 113 merges with the cooling air flowing into the first extraction pipe 113 through the swivel strengthening unit 201, but the cooling air is the first extraction pipe 113. Since they are swirling inside, they do not mix at once, but are gradually mixed as they progress downstream. That is, the cooling air advances while swirling the inner wall of the first extraction pipe 113, thereby forming an air curtain that prevents the high temperature cement kiln exhaust gas from coming into contact with the inner wall.

  The first extraction pipe 113 is cylindrical. This is because the cooling air that has flowed into the first extraction pipe 113 advances while swirling within the pipe. Cooling air flows from one of the plurality of cooling swirl air flow inlets 202 that are opened in a cylindrical shape on the tube wall of the first bleeder tube 113 or arranged at equal intervals in the circumferential direction. If the area of the cooling swirling air flow inlet 202 is small, the pressure loss increases and it becomes difficult to secure a necessary cooling air flow rate. Therefore, it is preferable that the area of the cooling swirling air flow inlet 202 is large.

  In the case of providing one cooling swirl air flow inlet 202 that is opened in a cylindrical shape, it can be formed by cutting the first extraction pipe 113 at two points in the cross-sectional direction. FIG. 2-2 shows a cross-sectional view of the cement kiln exhaust gas bleeder from the central axis direction of the bleeder tube 113 in this case. A circle drawn with a dotted line in the center indicates the position of the extracted bleeder tube wall. On the other hand, when a plurality of cooling swirling air flow inlets 202 are provided, it is desirable that a plurality of cooling swirl air flow inlets 202 be arranged at equal intervals in the circumferential direction of the first extraction pipe 113 so that the swirling flow is stabilized. It is desirable to have the same shape and size.

  A swirl strengthening unit 201 containing a plurality of swirl vanes 203 arranged at equal intervals in the circumferential direction has a concentric circle around the first extraction pipe 113 at a location where the swirl air flow inlet 202 for cooling is installed. It is installed to surround. The swirl vane 203 accommodated in the swirl strengthening unit 201 has a swirl flow along the inner wall of the first bleeder tube 113 as cooling air enters the first bleeder tube 113 through the cooling swirl airflow inlet 202. When the first bleeder tube 113 is observed from the central axis direction, the first bleeder tube 113 faces the tangential direction of the inner wall of the first bleeder tube 113 or the outside thereof.

  In order to suppress the backflow or reverse diffusion of the cooling air to the upstream side of the first bleed pipe 113, in one embodiment, each swirl vane observes the first bleed pipe 113 from the central axis direction, It is preferable that the first bleed pipe 113 faces outward by an angle α of 10 to 40 ° with respect to the tangential direction of the inner wall of the first bleed pipe 113. If this angle is less than 10 °, a sufficient swirling flow cannot be obtained, and if it exceeds 40 °, backflow tends to occur.

  In order to suppress the backflow or reverse diffusion of the cooling air to the upstream side of the first extraction pipe 113, in another embodiment, each swirl vane 203 is a cement kiln exhaust gas flowing in the first extraction pipe 113. Can be attached at an acute angle with respect to the flow direction, for example at an angle β of 1-10 °.

  In order to generate a uniform swirl flow in the circumferential direction in the first bleed pipe 113, the swirl vanes 203 are preferably arranged at equal intervals in the circumferential direction of the first bleed pipe 113. It is preferable to make them all in the same shape and size.

  Further, one cooling air conveying duct 205 arranged in a substantially tangential direction of the cylindrical outer wall of the turning strengthening unit 201 or arranged at equal intervals in the circumferential direction is in fluid communication. In order to generate a stable swirl flow in the first extraction pipe 113, it is preferable that a plurality of cooling air transfer ducts 205 are arranged at equal intervals in the circumferential direction of the swirl strengthening unit 201. If the number of cooling air transfer ducts 205 is large, the generated swirl flow can be stabilized and the required cooling air flow rate can be reduced as a whole, but the problem is that the space constraints and the duct layout are complicated. Therefore, it is preferable that the number of cooling air conveyance ducts 205 be about 2, 3, or 4.

  In view of the purpose of making the swirl flow flowing in the bleed pipe uniform in the circumferential direction, it is important that the number of swirl vanes 203 is larger than the number of cooling air transport ducts 205. Since the number of swirl vanes 203 is larger than the number of cooling air conveyance ducts 205, the cooling air is dispersed in the circumferential direction and sent to the first extraction pipe 113. Rather than being sent directly to the first bleed pipe 113 without passing through the blades 203, the cooling air flowing in from the cooling air transfer duct 205 has a uniform swirling flow in the circumferential direction in the first bleed pipe 113. It will be.

  For this reason, the number of swirl blades 203 should basically be large, but if the number is too large, the effect is substantially saturated, so about 15 to 36 sheets are common, and about 20 to 30 sheets are preferred.

  It is preferable that the swirl vane 203 is rotatably attached so as to be able to rotate around the first extraction pipe 113. As a result, the flow rate of the cooling air flowing into the first extraction pipe 113 via each swirl vane 203 is made more uniform, so that the swirl flow is also made uniform in the circumferential direction. For example, with respect to a cylindrical rotating body having an opening for allowing cooling air to smoothly rotate around the outer wall of the first extraction pipe 113 around the central axis of the first extraction pipe 113 Thus, the swirl vane 203 can be attached.

  When the swirl vane 203 rotates, the swirl vane 203 is lengthened, and the rotational speed is increased and the swirl flow is strengthened by shortening the distance between the cylindrical inner wall of the swirl reinforcing unit 201 and the tip of the swirl vane 203. For example, the distance from the central axis of the first bleed pipe 113 to its outer wall is D1, the distance from the central axis of the first bleed pipe 113 to the cylindrical inner wall of the swirl strengthening unit 201 is D2, and the radial direction of the swirl vane 203 D / (D2-D1) can be set to 0.5 or less, preferably 0.2 or less.

  On the other hand, when the swirl vane 203 is fixed without moving in the swirl strengthening unit 201, the cooling air flow flowing from the cooling air transfer duct 205 is interposed between the swirl vane 203 and the inner wall of the swirl unit. It is desirable to provide a sufficient clearance so as to spread throughout. Therefore, for example, d / (D2-D1) is preferably 0.5 or more.

<3. Second embodiment of cement kiln exhaust gas bleeder>
Next, a second embodiment of the cement kiln exhaust gas extraction apparatus according to the present invention will be described with reference to FIG. In addition to the apparatus configuration described in the first embodiment, the cement kiln exhaust gas extraction processing apparatus according to the second embodiment is connected to the first extraction pipe 113 on the downstream side of the cooling swirling air flow inlet 202. A concentric annular cooling straight air flow inlet 301 is provided. The straight air flow inlet 301 for cooling can be formed by concentrically inserting the downstream end of the first extraction pipe 113 into the second extraction pipe 302 having a larger diameter than the first extraction pipe 113. . The cooling air flows from the gap between the first extraction pipe 113 and the second extraction pipe 302 and travels straight along the inner wall of the second extraction pipe 302 in the same direction as the cement kiln exhaust gas.

  The air curtain that protects the inner wall of the extraction pipe from high-temperature cement kiln exhaust gas is strengthened by flowing a straight air flow in addition to the swirling air flow described above, so the temperature of the gas flow near the inner wall of the extraction pipe is lowered. And the effect of reducing the concentration of the cement kiln exhaust gas in the vicinity of the inner wall is enhanced. Further, when only the swirling air flow is used, the backflow of the cooling air is likely to occur, but the swirling air flow necessary for cooling can be reduced by using the straight air flow together. Therefore, there is an effect of preventing the cooling air from flowing backward.

  The cement kiln exhaust gas extraction apparatus according to the present invention can further include a cooling air conveyance pipe 303 that defines the flow of the cooling straight air flow. The cooling air conveying pipe 303 has a larger diameter than the first and second bleed pipes, surrounds the first and second bleed pipes in a concentric circle shape, and has a downstream end to allow cooling air to flow in. It is open. Then, after the cooling air that has flowed flows in the direction opposite to the flow direction of the cement kiln exhaust gas on the outer periphery of the second extraction pipe 302, the inlet of the first extraction pipe 113 and the second extraction pipe 302 is inserted. By the way, the upstream end is closed so that it can be reversed and headed toward the cooling straight air flow inlet 301. An effect of cooling the second extraction pipe 302 by the cooling air flowing on the outer periphery of the second extraction pipe 302 is obtained.

<4. Operation method of cement kiln exhaust gas extraction system>
It is desired that the cement kiln exhaust gas bleeder 101 is operated under conditions that can effectively suppress the occurrence of coating on the inside of the device, particularly the first and, if present, the inner wall of the second bleeder. For this purpose, first, the temperature of the mixed gas of the cooling air and the cement kiln exhaust gas contacting the inner wall of the first and second bleed pipes 302 is set to 350 at the downstream side of the cooling swirling air flow inlet 202. It is desirable to introduce cooling air at a flow rate sufficient to maintain the temperature below. If the temperature of the mixed gas in contact with the inner wall of the bleed pipe is 350 ° C or lower, volatile components such as alkali chlorides and alkali sulfates are completely solidified to form a powder. It can be substantially prevented.

  In addition, the concentration of the cement kiln exhaust gas in the mixed gas contacting the inner wall of the first and second bleed pipes, if present, is such that the cooling air and the cement kiln are downstream of the cooling swirl air flow inlet 202. Until the temperature of the hottest part of the mixed gas of the exhaust gas (generally near the central axis of the bleed pipe) is cooled to 350 ° C. or less, it is kept below 10% by volume, preferably below 5% by volume. Adjusting the cooling air flow rate is desirable for suppressing the occurrence of coating. In other words, if the hottest part of the mixed gas is 350 ° C. or less, there is no need to worry about the concentration of the cement kiln exhaust gas in the mixed gas contacting the inner wall. Cooling air and cement kiln exhaust gas can be mixed at once. At this time, there is almost no worry about the occurrence of coating. The generated powder can be collected by providing a dust collector 115 upstream of the exhaust suction device.

According to the examination result of the present inventor, when operating the cement kiln exhaust gas bleeder processing apparatus 101 according to the first embodiment of the present invention, the cross-sectional area of the first bleed pipe 113 is Ae (m ² ), The average flow velocity of the cement kiln exhaust gas flowing through the inlet of one extraction pipe 113 is Ue (m / s), the density is ρe (kg / m ³ ), the number of cooling air transfer ducts 205 is N (main), and the cooling air transfer When the sectional area per duct 205 is At (m ² ), the average flow velocity of cooling air at the outlet of the cooling air conveyance duct 205 is Ut (m / s), and the density is ρt (kg / m ³ ). ,
(At · N · ρt · Ut ² ) / (Ae · ρe · Ue ² ) = 0.35-10, preferably 1-10
And N ≧ 2
By operating the cement kiln exhaust gas extraction device under conditions that satisfy the above conditions, a uniform swirling flow is generated in the extraction pipe, and the air curtain can be stably maintained.

According to the examination results of the present inventors, when operating the cement kiln exhaust gas extraction apparatus 101 according to the second embodiment of the present invention, the sectional area of the first extraction pipe 113 is Ae (m ² ), The average flow velocity of the cement kiln exhaust gas flowing through the inlet of one extraction pipe 113 is Ue (m / s), the density is ρe (kg / m ³ ), the number of cooling air transfer ducts 205 is N (main), and the cooling air transfer The cross-sectional area per duct 205 is At (m ² ), the average flow velocity of cooling air at the outlet of the cooling air conveyance duct 205 is Ut (m / s), the density is ρt (kg / m ³ ), and for cooling The cross-sectional area of the straight air flow inlet 301 is Ad (m ² ), the average flow velocity of the cooling air in the cooling straight air flow inlet 301 is Ud (m / s), and the density is ρd (kg / m ³ ). When
(At · N · ρt · Ut ² ) / (Ae · ρe · Ue ² ) = 0.15 to 5, preferably 0.15 to 4 and (Ad · ρd · Ud ² ) / (Ae · ρe · Ue ² ) = 2.2-360, preferably 2.2-100
And N ≧ 2
By operating the cement kiln exhaust gas extraction device under conditions that satisfy the above conditions, a uniform swirling flow is generated in the extraction pipe, and the air curtain can be stably maintained.

  Moreover, in an example of the operating conditions of the cement kiln exhaust gas extraction apparatus according to the present invention, the ratio of the cooling air flow rate (N · At · Ut + Ad · Ud) to the extraction flow rate (Ae · Ue) can be set to 1 to 10. In a typical example, it can be 1 to 5, and further can be 1 to 2. That is, according to the present invention, a uniform swirling flow of cooling air is obtained and a stable air curtain is formed, so that the amount of cooling air required to prevent the occurrence of coating can be reduced.

  The cooling air may be supplied by providing a blower upstream of the cooling air conveyance duct 205 and / or the cooling air conveyance pipe 303 so as to push the cooling air into the extraction pipe. From this point of view, it is also possible to supply the suction pipe by drawing it into a negative pressure by using a suction force from an exhaust suction device connected directly or indirectly downstream of the extraction pipe. Although the exhaust suction device can be provided individually, as shown in FIG. 1, it is easy to make the exhaust suction device 108 for the main exhaust duct of the cement kiln facility also serve as a simpler device. .

  An embodiment of the present invention using a computer (SCRYU Tetra software manufactured by CRADLE) will be described below.

<Example 1 (comparison): Cement kiln exhaust gas extraction device without swivel strengthening unit>
The temperature distribution in the extraction pipe and the concentration distribution of the exhaust gas were examined by computer simulation when a cement kiln exhaust gas extraction processing apparatus without a swirl strengthening unit as exemplified in FIGS. 4-1 and 4-2 was used. The extraction processing apparatus has one cooling swirl air flow inlet that is opened in a cylindrical shape. The operating conditions of the device are as follows.
・ Bleeding tube cross-sectional area Ae: 0.196 m ²
・ Bleeding flow velocity Ue: 13.2 m / s
・ Cement kiln exhaust gas density ρe: 0.259 kg / m ³
・ Number of cooling air conveyance ducts: 2 (equal spacing)
・ Cross sectional area of air conveying duct for cooling At: 0.04 m ² / line ・ Swirl air flow velocity for cooling Ut: 9.48 m / s
・ Swirl air density for cooling ρt: 1.23 kg / m ³
・ Cement kiln exhaust gas temperature: 1100 ℃
・ Swirl air temperature for cooling: 20 ℃

  As a result of the simulation, it was found that the gas temperature on the upstream side of the cooling swirling air flow inlet decreased. This indicates that the cooling air is flowing backward through the extraction pipe. Further, the gas temperature in this vicinity is distributed from about 1100 ° C. to about 150 ° C. from the upstream side to the downstream side, and the gas at 400 to 900 ° C. that is likely to be coated is in contact with the inner wall of the extraction pipe. It was observed. Moreover, the exhaust gas concentration in the 400-900 degreeC mixed gas which is contacting the bleeder pipe inner wall was high, and was 10 volume% or more.

<Example 2 (Invention Example): Cement kiln exhaust gas extraction processing apparatus provided with a swirl strengthening unit>
Compared to Example 1, the temperature distribution in the extraction pipe and the concentration distribution of the exhaust gas when the cement kiln exhaust gas extraction processing apparatus provided with the swirl strengthening unit of the type illustrated in FIGS. It was investigated by simulation. The operating conditions of the apparatus were the same as in Example 1 except that swirl vanes were provided under the following conditions.
・ Number of swirling blades: 24 (equal intervals)
・ Angle α relative to the tangential direction of each swirl blade: 60 °
・ An angle β of each swirl vane with respect to the flow direction of exhaust gas: 0 °
・ Swivel blade rotation: None ・ Clearing d / (D2-D1): 0.5

  As a result of the simulation, the cooling air was observed to flow backward through the bleed pipe. However, when the isotherm in the bleed pipe is observed from the central axis direction of the bleed pipe, the disturbance is less than in Example 1 and approaches a concentric circle. It was.

<Example 3 (invention example): Cement kiln exhaust gas extraction device provided with a swirl strengthening unit>
The operating conditions were the same as in Example 2 except that the angle α with respect to the tangential direction of each swirl vane was 30 °.

  As a result of the simulation, the backflow of the cooling air was significantly suppressed as compared with Example 1. In addition, when the isotherm in the bleed tube was observed from the central axis direction of the bleed tube, the disturbance was less than that in Example 1, and the concentric shape was approached.

<Example 4: Combined use of swirling air and straight air>
The temperature distribution in the extraction pipe and the concentration distribution of the exhaust gas when using the cement kiln exhaust gas extraction processing device of the type illustrated in FIG. 3 provided with a swirl strengthening unit and further provided with a straight air flow inlet for cooling is calculated by computer simulation. Examined. Here, the total flow rate of the swirling air flow and the straight air flow was approximately 3 m ³ / s, and the ratio of the swirling air flow and the straight air flow was changed.
The operating conditions of the device are as follows.
・ Bleeding tube cross-sectional area Ae: 0.196 m ²
・ Bleeding flow velocity Ue: 13.2 m / s
・ Cement kiln exhaust gas density ρe: 0.259 kg / m ³
・ Cooling air transport ducts: 4 (equal spacing)
・ Cross-air conveyance duct cross-sectional area At: 0.04 m ² / line ・ Cooling swirl air flow velocity Ut: See Table 1 ・ Cooling swirl air density ρt: See Table 1 ・ Cooling straight air flow inlet cross-sectional area Ad: 0.0306m ²
・ Cooling straight air flow velocity Ud: See Table 1 ・ Cooling straight air density ρd: See Table 1 ・ Cement kiln exhaust gas temperature: 1100 ° C.
・ Swirl air temperature for cooling: 20 ℃
・ Number of swirling blades: 24 (equal intervals)
・ Angle α relative to the tangential direction of each swirl blade: 30 °
・ An angle β of each swirl vane with respect to the flow direction of exhaust gas: 0 °
・ Swivel blade rotation: None ・ Clearing d / (D2-D1): 0.5

The simulation results are shown in Table 1. When flowing the same amount of cooling air, the gas temperature and exhaust gas concentration in the vicinity of the inner wall of the extraction pipe are kept lower in the swirl flow alone or the combination of the straight flow and the swirl flow, rather than the straight flow alone. The air curtain retention effect was high. Moreover, the holding effect of the air curtain improved as the swirl flow ratio increased. On the other hand, the higher the ratio of straight flow, the less backflow. For reference, no. An isotherm diagram of 4-4 is shown in FIG. 5, and an isoconcentration diagram is shown in FIG.
In the evaluation, there is no gas exceeding 350 ° C. in contact with the inner wall of the bleed pipe on the downstream side of the cooling swirling air flow inlet, and the temperature of the hottest portion of the gas is cooled to 350 ° C. or lower. ◎ When the cement kiln exhaust gas concentration in contact with the inner wall of the extraction pipe can be maintained at less than 10% by volume, 350 ° C. in contact with the inner wall of the extraction pipe on the downstream side of the cooling swirling air flow inlet ◯ when there is no excess gas, △ when there is a part of the gas that exceeds 350 ° C in contact with the inner wall of the extraction pipe on the downstream side of the cooling swirling air flow inlet, and introducing the swirling air flow for cooling The case where there was a lot of gas exceeding 350 ° C. in contact with the inner wall of the bleed pipe on the downstream side of the mouth was marked as x.

<Example 5: Influence of the total amount of cooling air to be introduced>
The temperature distribution in the extraction pipe and the concentration distribution of the exhaust gas were examined by computer simulation when a cement kiln exhaust gas extraction processing apparatus equipped with a swirl strengthening unit and further provided with a straight air flow inlet for cooling was used. Here, the total flow rate of the swirling air flow and the straight air flow was changed.
The operating conditions of the device are as follows.
・ Bleeding tube cross-sectional area Ae: 0.196 m ²
・ Bleeding flow velocity Ue: 13.2 m / s
・ Cement kiln exhaust gas density ρe: 0.259 kg / m ³
・ Cooling air transport ducts: 4 (equal spacing)
・ Cross-air conveyance duct cross-sectional area At: 0.04 m ² / line ・ Cooling swirl air flow velocity Ut: See Table 2 ・ Cooling swirl air density ρt: See Table 2 ・ Cooling straight air flow inlet cross-sectional area Ad: 0.0306m ²
・ Cooling straight air flow velocity Ud: See Table 2 ・ Cooling straight air density ρd: See Table 2 ・ Cement kiln exhaust gas temperature: 1100 ° C.
・ Swirl air temperature for cooling: 20 ℃
・ Number of swirling blades: 24 (equal intervals)
・ Angle α relative to the tangential direction of each swirl blade: 30 °
・ An angle β of each swirl vane with respect to the flow direction of exhaust gas: 0 °
・ Swivel blade rotation: None ・ Clearing d / (D2-D1): 0.5

  The simulation results are shown in Table 2. As the total cooling air flow rate increased, the gas temperature and exhaust gas concentration in the vicinity of the inner wall of the extraction pipe were kept low toward the downstream, and the air curtain retention effect was high. In view of the balance between effect and economic efficiency, There is no need to increase the air flow rate beyond 5-4.

<Example 6: Influence of the number of cooling air conveyance ducts>
The temperature distribution in the extraction pipe and the concentration distribution of the exhaust gas were examined by computer simulation when a cement kiln exhaust gas extraction processing apparatus equipped with a swirl strengthening unit and further provided with a straight air flow inlet for cooling was used. Here, the total flow rate of the swirling air flow and the straight air flow was set to approximately 3 m ³ / s, and the number of cooling air conveyance ducts was changed.
The operating conditions of the device are as follows.
・ Bleeding tube cross-sectional area Ae: 0.196 m ²
・ Bleeding flow velocity Ue: 13.2 m / s
・ Cement kiln exhaust gas density ρe: 0.259 kg / m ³
・ Number of cooling air transport ducts: see Fig. 3 (Equal spacing)
・ Cross-air conveyance duct cross-sectional area At: 0.04 m ² / line ・ Cooling swirl air flow velocity Ut: See Table 3 ・ Cooling swirl air density ρt: See Table 3 ・ Cooling straight air flow inlet cross-sectional area Ad: 0.0306m ²
・ Cooling straight air flow velocity Ud: See Table 3 ・ Cooling straight air density ρd: See Table 3 ・ Cement kiln exhaust gas temperature: 1100 ° C.
・ Swirl air temperature for cooling: 20 ℃
・ Number of swirling blades: 24 (equal intervals)
・ Angle α relative to the tangential direction of each swirl blade: 30 °
・ An angle β of each swirl vane with respect to the flow direction of exhaust gas: 0 °
・ Swivel blade rotation: None ・ Clearing d / (D2-D1): 0.5

  The simulation results are shown in Table 3. Even when the total cooling air flow rate was the same, as the number of cooling air conveyance ducts increased, the gas temperature and exhaust gas concentration in the vicinity of the inner wall of the extraction pipe were kept low toward the downstream, and the air curtain retention effect was high.

101 Cement Kiln Exhaust Gas Extractor 102 Rotary Kiln 103 Preheater 104 Kiln Inlet Hood 105 Rising Duct 106 Calciner 107 Cyclone 108 Exhaust Suction Device 109 Dryer 110 Stabilizer 111 Electric Dust Collector 112 Cement Kiln Exhaust Gas Extractor 113 First Extraction Pipe 114 Suction Duct 115 Dust collector 201 Swirling strengthening unit 202 Cooling swirl air flow inlet 203 Swirling blade 205 Cooling air transport duct 301 Cooling straight airflow inlet 302 Second extraction pipe 303 Cooling air transport pipe

Claims (13)

A cement kiln exhaust gas extraction processing device that extracts a part of cement kiln exhaust gas, mixes the extracted exhaust gas with cooling air, and lowers the exhaust gas temperature for processing.
A cylindrical first extraction pipe for extracting a part of the cement kiln exhaust gas;
A plurality of swirling air flow inlets for cooling arranged in a cylindrical shape in the pipe wall of the first bleed pipe, or arranged at equal intervals in the circumferential direction;
A swirl strengthening unit that concentrically surrounds the first bleed pipe at the location where the swirling air flow inlet for cooling is installed, and contains a plurality of swirl vanes arranged at equal intervals in the circumferential direction, and Each swirl vane has a first swirl flow that allows cooling air to enter the first bleed pipe from the cooling swirl air flow inlet and create a swirl flow along the inner wall of the first bleed pipe. Facing the tangential direction of the inner wall of the bleed pipe or the outside of it,
One cooling air conveyance duct arranged in fluid communication in the substantially tangential direction of the outer wall of the swirl strengthening unit or a plurality of cooling air conveyance ducts arranged at equal intervals in the circumferential direction, where the number of swirl vanes is the cooling air conveyance duct More than the number of
A cement kiln exhaust gas bleed processing device.   The cement kiln exhaust gas extraction processing apparatus according to claim 1, wherein each swirl vane is directed outward by an angle of 10 to 40 degrees with respect to a tangential direction of the inner wall of the first extraction pipe.   3. The cement kiln exhaust gas extraction apparatus according to claim 1, wherein each swirl blade is attached at an acute angle with respect to a flow direction of the cement kiln exhaust gas flowing in the first extraction pipe.   The cement kiln exhaust gas extraction apparatus according to any one of claims 1 to 3, wherein the number of cooling air conveyance ducts is two, three, or four.   The cement kiln exhaust gas extraction processing apparatus according to any one of claims 1 to 4, wherein the number of swirling blades is 15 to 36.   The cement kiln exhaust gas extraction processing apparatus according to any one of claims 1 to 5, wherein the swirl vane is rotatably attached so as to be able to rotate around the first extraction pipe.   A cooling straight air flow inlet that is concentric with the first bleed pipe is further provided on the downstream side of the cooling swirl air flow inlet, and the cooling straight air flow inlet is more than the first bleed pipe. The cement kiln exhaust gas extraction processing apparatus according to any one of claims 1 to 6, wherein a downstream end of the first extraction pipe is concentrically inserted into a second extraction pipe having a large pipe diameter.   A cooling air carrier pipe that defines the flow of the straight air flow for cooling is further provided downstream of the swirl strengthening unit, and the cooling air carrier pipe has a larger diameter than the first and second bleed pipes. And the second extraction pipe is concentrically surrounded, the downstream end is opened to allow cooling air to flow in, and the flowing cooling air flows around the outer periphery of the second extraction pipe into the cement kiln exhaust gas flow. After flowing in the direction opposite to the direction, the upstream tip is closed so that it can be reversed at the insertion port of the first bleed pipe and the second bleed pipe and go to the straight air flow inlet for cooling. The cement kiln exhaust gas extraction processing apparatus according to claim 7. The operation method of the cement kiln exhaust gas extraction apparatus according to any one of claims 1 to 6, wherein the cross-sectional area of the first extraction pipe is Ae (m ² ), and the cement kiln exhaust gas flowing through the first extraction pipe inlet The average flow velocity is Ue (m / s), the density is ρe (kg / m ³ ), the number of cooling air conveyance ducts is N (lines), and the cross-sectional area per cooling air conveyance duct is At (m ² ) When the average flow velocity of cooling air at the outlet of the cooling air conveyance duct is Ut (m / s) and the density is ρt (kg / m ³ ),
(At · N · ρt · Ut ² ) / (Ae · ρe · Ue ² ) = 0.35-10
N ≧ 2
A method of operating a cement kiln exhaust gas extraction device under conditions that satisfy the above conditions. The operation method of the cement kiln exhaust gas extraction apparatus according to claim 7 or 8, wherein the cross-sectional area of the first extraction pipe is Ae (m ² ), and the average flow velocity of the cement kiln exhaust gas flowing through the first extraction pipe inlet is Ue (m / s), density ρe (kg / m ³ ), number of cooling air conveyance ducts N (lines), sectional area per cooling air conveyance duct At (m ² ), cooling The average flow velocity of the cooling air at the outlet of the air conveyance duct is Ut (m / s), the density is ρt (kg / m ³ ), the cross-sectional area of the straight air flow inlet for cooling is Ad (m ² ), and the straight line for cooling When the average flow velocity of the cooling air at the air flow inlet is Ud (m / s) and the density is ρd (kg / m ³ ),
(At · N · ρt · Ut ² ) / (Ae · ρe · Ue ² ) = 0.15-5
And (Ad · ρd · Ud ² ) / (Ae · ρe · Ue ² ) = 2.2 to 360
N ≧ 2
A method of operating a cement kiln exhaust gas extraction device under conditions that satisfy the above conditions.   10. The temperature of the mixed gas of cooling air and cement kiln exhaust gas contacting the inner wall of the first and second bleed pipes, if present, is maintained at 350 ° C. or lower downstream of the cooling swirling air flow inlet. Or the driving | operation method of 10.   For the mixed gas of cooling air and cement kiln exhaust gas contacting the inner wall of the first and second bleed pipes if present, the concentration of the cement kiln exhaust gas is measured downstream of the swirling air flow inlet for cooling. The operation method according to any one of claims 9 to 11, wherein the temperature is maintained at less than 10% by volume until the temperature of the hottest portion is cooled to 350 ° C or lower.   For the main exhaust duct of a cement kiln facility connected directly or indirectly downstream of the swirling air flow for cooling and, if present, for cooling straight air flow, and for the first and, if present, for the second extraction pipe The operation method according to any one of claims 9 to 12, wherein the operation is generated by setting the inside of the extraction pipe to a negative pressure by a suction force from the exhaust suction device.