JP5806029B2 - Cement kiln exhaust gas extraction treatment apparatus and its operation method - Google Patents

Description

  The present invention occurs, for example, on an inner wall surface of a preheater when 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 device, 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 tip of the extraction pipe on the kiln bottom side is described. Cooling air sufficient to cool the exhaust gas temperature at the outlet of the chamber to 350 ° C. or lower was blown from the outer periphery of the cooling chamber so as to generate a swirling flow of cooling air along the wall surface, and connected to the cooling chamber. The exhaust gas and the cooling air are gradually mixed by maintaining the swirling flow in the cooling chamber outlet duct, and then introduced into the chamber, and the exhaust gas and the cooling air are mixed by disturbing the swirling flow. Disclosed is a method for treating a bleed cement kiln exhaust gas, which is cooled to 350 ° C. or lower 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 from the outer periphery of the cooling chamber along the inner wall surface 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. about.
(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. Have been described.
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). Patent Document 2 discloses that in this method, the flow rate of the cooling gas is made slower than the flow rate on the inner pipe side (Claim 2), and the discharge flow rate of the cooling gas in the probe longitudinal direction is 1 of the flow rate of the extracted gas in the inner tube. / 3 to 2/3 (Claim 3) and the cooling gas as a swirl flow (Claim 4) are also disclosed.
Further, Patent Document 2 includes a probe having a double-pipe structure communicating with a kiln exhaust gas flow path, and the probe extracts an inner pipe from which a part of the kiln exhaust gas is extracted, and an outer pipe protruding from the tip of the inner pipe And an exhaust gas cooling device having a fluid passage formed between the inner tube and the outer tube and supplied with cooling gas, provided with guiding means for guiding the cooling gas to the inside of the tip of the inner tube, An exhaust gas cooling device in a kiln bypass characterized in that a mixed quenching region is formed at the tip of the probe is disclosed (claim 5). In Patent Document 2, in the exhaust gas cooling apparatus, the guide means is a tip portion of an outer tube that gradually decreases in diameter toward the tip (Claim 6), and the guide means is connected to the tip portion of the inner tube and the outer portion. It is comprised by the inclination board provided between the front-end | tip parts of a pipe | tube, and the cooling air hole provided in the front-end | tip part of an inner pipe. (Claim 7), The inclination board is equipped with the air hole for probe tip protection. (Claim 8) The probe tip protection cooling means is provided at the tip of the outer tube (Claim 9), and the probe tip protection cooling means is a ring-shaped water-cooled tube (Claim 10). Is also disclosed.
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). It is also described that the extraction gas is rapidly cooled to the melting point 600-700 ° C. of the chlorine compound in the mixed quenching zone (paragraph 0026).

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).

In Japanese Patent No. 4435273 (Patent Document 4), a cylindrical first extraction pipe for extracting a part of the cement kiln exhaust gas, and a cylindrical opening on the tube wall of the first extraction pipe are provided. Alternatively, a plurality of cooling swirling air flow inlets arranged at equal intervals in the circumferential direction and a concentric circle around the first bleeder pipe at a place where the cooling swirling air flow inlets are installed, A swirl strengthening unit containing a plurality of swirl vanes arranged at equal intervals in the circumferential direction (here, each swirl vane enters the first bleed pipe from the swirl air flow inlet for cooling into the first extraction pipe) The tangential direction of the inner wall of the first bleed pipe or the outside thereof so that a swirl flow along the inner wall of the one bleed pipe can be generated. One in fluid communication in the direction, or evenly in the circumferential direction A cement kiln exhaust gas bleed processing device is proposed that includes a plurality of cooling air conveyance ducts arranged in the above (where the number of swirl vanes is larger than the number of cooling air conveyance ducts). 1).
According to this invention, in order to remove the volatile components such as alkali chlorides and alkali sulfates contained in the cement kiln exhaust gas, in order to remove the cement kiln exhaust gas with a bleed pipe, a chlorine bypass method of extracting part of the cement kiln exhaust gas, A uniform swirling flow can be easily generated. In addition, it is also described that a straight air flow is flowed in addition to a swirl air flow to prevent the cooling air from flowing backward in the extraction pipe (paragraph 0046).

JP-A-9-175847 JP-A-11-35355 JP 2001-335348 A Japanese Patent No. 4435273

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. It is also described 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.
However, in the structure of the cooling chamber described in Patent Document 1, if the number of air blowing ports is increased, the piping layout of the cooling air becomes complicated and the cost becomes high, and it is a reality that a large number of blowing ports are provided due to space constraints. Not right. In addition, it is aimed to suppress the generation of coating on the inner wall of the extraction pipe by causing the swirling flow to flow backward from the cooling chamber toward the leading end of the extraction pipe. However, in the cooling chamber structure described in Patent Document 1, When the working air flows backward, mixing with the cement kiln exhaust gas tends to cause the temperature of the gas in contact with the inner wall of the extraction pipe to fall within a range of 400 to 900 ° C. at which coating is likely to be generated.

In Patent Document 2, a probe having a double pipe structure is communicated with a kiln exhaust gas flow path, and a part of the kiln exhaust gas is extracted through the inner pipe of the probe, and between the inner pipe and the outer pipe of the probe. In the exhaust gas cooling method in the kiln bypass that supplies the cooling gas to the fluid passage of the inner pipe, in order to guide the cooling gas to the inside of the tip portion of the inner tube, the tip portion of the outer tube that gradually becomes smaller in diameter toward the tip may be used. Have been described.
However, Patent Document 2 intends to mix the extracted gas at the tip of the probe and instantaneously cool it to the melting point 600 to 700 ° C. In such a temperature state, the inner wall of the probe may be coated. Sex is great. That is, the method described in Patent Document 2 employs a method in which the cooling gas and the extraction gas are mixed together at the tip of the probe, so that the mixed gas flowing through the inner tube is in a state where the swirl flow is disturbed. It is difficult to form an air curtain sufficient to prevent the coating from adhering to the inner wall of the glass.

  In the structure of the cement kiln exhaust gas bleeder described in Patent Document 3, there is no risk of coating in the bleeder pipe because there is no allowance for the exhaust gas in the bleeder pipe upstream from the tip of the suction duct. high. Further, since the air curtain due to the swirling flow is not generated in the suction duct, the effect of suppressing the coating is not sufficient.

  In the cement kiln exhaust gas extraction device described in Patent Document 4, a swirl flow along the inner wall of the extraction pipe for cooling air is uniformly formed, and an air curtain for protecting the inner wall of the extraction pipe from the high-temperature cement kiln exhaust gas is provided in the extraction pipe. The coating on the downstream side from the cooling air flow inlet is suppressed by maintaining the axial direction for a long time, but the swirl flow along the inner wall of the extraction pipe of the cooling air is upstream from the cooling air flow inlet. As a result, the concern about the generation of coating remains.

  Then, this invention makes it a subject to provide the cement kiln exhaust gas extraction processing apparatus which can prevent effectively the coating generation | occurrence | production in the upstream and downstream of a cooling airflow inlet, and its operating method.

In one aspect of the present invention, a cement kiln for extracting a part of the cement kiln exhaust gas from a cement kiln exhaust gas flow path in which the cement kiln exhaust gas flows upward, mixing the extracted exhaust gas with cooling air, and reducing the exhaust gas temperature for processing. An exhaust gas extraction device,
a) A cylindrical body having an inlet for introducing cooling air on its side surface, and a concentric shaft connected to the upstream side of the body, and the cooling air introduced from the inlet is swirled. A cyclone having a tapered portion for flowing toward the upstream side, wherein the tip of the tapered portion of the cyclone is in communication with the cement kiln exhaust gas flow path;
b) a bleed tube partially inserted concentrically from the downstream side toward the upstream side of the cyclone body; and c) concentrically connected to the upstream end of the tapered portion of the cyclone, and upstream. A reverse-tapered cement kiln exhaust gas introduction wall with an increasing inner diameter, wherein the cement kiln exhaust gas introduction wall is formed in the cement kiln exhaust gas passage;
It is the cement kiln exhaust gas extraction processing apparatus provided with.

  In one embodiment of the cement kiln exhaust gas extraction apparatus according to the present invention, when the angle of the central axis of the cement kiln exhaust gas extraction apparatus with respect to the horizontal plane is θ °, 20 ° ≦ θ ° ≦ 70 °.

  In another embodiment of the cement kiln exhaust gas extraction apparatus according to the present invention, the expansion angle α ° of the cement kiln exhaust gas introduction wall with respect to the central axis of the cement kiln exhaust gas extraction apparatus is 5 ° ≦ α ° ≦ 90−θ. °.

  In still another embodiment of the cement kiln exhaust gas extraction apparatus according to the present invention, α ° = 90−θ °.

  In still another embodiment of the cement kiln exhaust gas extraction apparatus according to the present invention, the length H of the bus bar of the cement kiln exhaust gas introduction wall is larger than ½ of the inner diameter D1 of the tip of the tapered portion of the cyclone.

  According to another aspect of the present invention, there is provided a method for operating the above-described cement kiln exhaust gas extraction apparatus, wherein the cooling air flows into the cyclone from the cooling air inlet of the body portion of the cyclone, The cooling air that has flown into the cyclone advances upstream while swirling the inner wall of the cyclone, changes direction at the tip of the tapered portion, and further proceeds downstream while swirling the inner wall of the extraction pipe; A part of the cement kiln exhaust gas flows from the cement kiln exhaust gas flow path through the cement kiln exhaust gas introduction wall into the cyclone, and the cement kiln exhaust gas flowing into the cyclone is mixed with the cooling air swirling around it. The operation method including the process to be performed.

  In one embodiment of the operation method of the cement kiln exhaust gas extraction apparatus according to the present invention, the temperature of the mixed gas of cooling air and cement kiln exhaust gas contacting the inner wall of the cyclone and the inner wall of the extraction pipe is maintained at 350 ° C. or lower. .

  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, The occurrence of coating on the upstream side and downstream side of the cooling airflow inlet can be effectively prevented.

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 a schematic diagram when one embodiment of the cement kiln exhaust gas extraction apparatus according to the present invention is viewed from a vertical section passing through the central axis. 1 is a schematic view of an embodiment of a cement kiln exhaust gas extraction apparatus according to the present invention when a cooling air introduction port installed in a body part of a cyclone is viewed from a cross section perpendicular to a central axis. It is a schematic diagram when it sees from the vertical cross section which passes along a center axis | shaft about the cement kiln waste gas extraction processing apparatus in Example 1 (comparative example). It is a schematic diagram which shows a 350 degreeC isotherm about the cement kiln waste gas extraction processing apparatus in Example 1 (comparative example). It is a schematic diagram which shows an isotherm of 350 degreeC about the cement kiln waste gas extraction processing apparatus in Example 2 (invention example). It is a schematic diagram when it sees from the vertical cross section which passes along a center axis | shaft about the cement kiln waste gas extraction processing apparatus in Examples 3-6 (invention example). It is a schematic diagram which shows an isotherm of 350 degreeC about the cement kiln waste gas extraction processing apparatus in Example 7 (invention example).

  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 102, a rising duct 105 extending right above the kiln inlet hood 104, A pre-calcining furnace 106 for pre-calcining the preheated cement raw material and a cyclone 107 are sequentially passed along the 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 108, it is exhausted from the chimney through the dryer 109, the stabilizer 110, and the electrostatic precipitator 111.

  The cement kiln exhaust gas extraction port 112 can be provided on any wall surface of the cement kiln exhaust gas flow path through which the cement kiln exhaust gas flows upward, such as the kiln inlet hood 104, the rising duct 105, and the calcining furnace 106. Since the volatile component that causes the generation of the coating is in a temperature range in which it is easy to concentrate in the kiln exhaust gas, it is preferable to extract from the wall surface of the kiln inlet hood 104 or the rising duct 105. Moreover, it is preferable to attach the cement kiln exhaust gas treatment extraction device 101 to the wall surface on the cement kiln side (the wall surface on the right side in FIG. 1) for the reason that the flow rate of the kiln exhaust gas is relatively slower than the mainstream.

  Although there is no restriction | limiting in particular in the attachment direction of the cement kiln exhaust gas treatment extraction apparatus 101, Since exhaust gas flows upwards, it is preferable to attach so that exhaust gas is extracted in the diagonally upward direction. However, it is also possible to install the exhaust gas in the horizontal direction. When the exhaust gas is attached so as to be extracted in an obliquely upward direction, if the angle of the central axis of the cement kiln exhaust gas extraction device inserted into the cement kiln exhaust gas flow path with respect to the horizontal plane is θ °, 0 <θ ° <90 However, if θ is too small, it is difficult to extract the cement kiln exhaust gas in the upward direction. On the other hand, if θ is too large, the structure of the apparatus becomes complicated from the viewpoint of the installation space of the extraction device. ≦ θ ° ≦ 70 ° is preferable, and 30 ° ≦ θ ° ≦ 60 ° is more preferable.

<2. Cement kiln exhaust gas extraction system>
Next, an embodiment of the cement kiln exhaust gas extraction apparatus according to the present invention will be described with reference to FIGS. FIG. 2 is a schematic view of the cement kiln exhaust gas extraction treatment apparatus 101 according to this embodiment connected to the rising duct 105 as viewed from a vertical cross section passing through the central axis. FIG. 3 is a schematic view of the cooling air inlet installed in the body of the cyclone from a cross section perpendicular to the central axis of the cement kiln exhaust gas extraction apparatus 101 according to the present embodiment. In the present specification, the direction in which the extracted cement kiln exhaust gas flows through the cement kiln exhaust gas extraction processing device is downstream, and the reverse is upstream.

  The cement kiln exhaust gas extraction processing apparatus 101 is connected to a cylindrical body 122 having an inlet 121 for introducing cooling air 130 on its side surface, and a concentric shaft on the upstream side of the body 122, and the introduction A cyclone 120 having a truncated cone-shaped tapered portion 124 for flowing the cooling air 130 introduced from the port 121 toward the upstream side while swirling is provided. The cement kiln exhaust gas bleeder 101 is in communication with the rising duct 105 because the tip 123 of the tapered portion 124 is partially inserted into the rising duct 105 obliquely from above. Further, the cement kiln exhaust gas extraction processing apparatus 101 includes an extraction pipe 128 partially inserted concentrically from the downstream side toward the upstream side in the body portion 122 of the cyclone 120.

  Operation | movement of the cement kiln exhaust gas extraction processing apparatus 101 which has such a structure is demonstrated. The cooling air 130 that has flowed in from the inlet 121 of the cooling air 130 travels upstream while turning in the cyclone 120, and turns downstream at the tip 123 of the tapered portion 124. The cooling air 130 toward the downstream side becomes a swirling flow having a diameter corresponding to the inner diameter D1 of the tip 123 of the tapered portion 124, and the cyclone is swirling in a region closer to the central axis than the cooling air 130 toward the upstream side. Proceed through 120 and into the extraction tube 128. That is, the cooling air 130 advances upstream while swirling the inner wall of the cyclone 120, changes direction at the tip 123, and further proceeds downstream while swirling the inner wall of the extraction pipe 128. 120, an air curtain is formed to prevent high temperature cement kiln exhaust gas from contacting the inner wall of the extraction pipe 128.

  On the other hand, the cement kiln exhaust gas 131 flowing in the rising duct 105 flows into the cyclone 120 so as to be sucked into the central axis portion of the tip 123 having the tapered portion 124 opened. The cement kiln exhaust gas 131 that has flowed into the cyclone 120 is cooled by mixing with the cooling air 130, but the cooling air 130 maintains a swirling flow even after the direction is changed. It does not mix with the cooling air 130 at a stretch, but gradually mixes with the cooling air 130 swirling around the center axis of the cyclone 120 while flowing downstream.

  Further, the cement kiln exhaust gas extraction apparatus 101 is connected to the tip 123 of the taper portion 124 inserted into the rising duct 105 in a concentric shaft shape, and introduces a reverse-tapered cement kiln exhaust gas whose inner diameter increases toward the upstream side. It has a wall 125. In the present embodiment, the space formed by the cement kiln exhaust gas introduction wall 125 has a truncated cone shape with the opening surface formed by the tip 123 of the tapered portion 124 as the bottom surface. As can be seen from FIG. 2, the cement kiln exhaust gas introduction wall 125 is formed in the cement kiln exhaust gas flow path.

  The cement kiln exhaust gas 131 rising in the rising duct 105 is slowed down by the fluid resistance provided by the introduction wall 125. As a result, the cement kiln exhaust gas 131 that has flowed into the cyclone 120 is easy to flow straight without meandering, so that high-temperature gas is less likely to contact the inner walls of the cyclone 120 and the extraction pipe 128.

  That is, in the state where the cement kiln exhaust gas introduction wall 125 does not exist, the cement kiln exhaust gas 131 flows into the opening of the tip 123 of the tapered portion 124 with a high flow rate in the upward direction. When the kiln exhaust gas 131 meanders, the air curtain by the cooling air 130 is likely to be disturbed, and high-temperature gas easily comes into contact with the inner walls of the cyclone 120 and the extraction pipe 128. On the other hand, the presence of the cement kiln exhaust gas introduction wall 125 reduces the upward flow rate of the cement kiln exhaust gas 131 flowing into the opening of the tip 123 of the tapered portion 124, thereby reducing the straightness of the inflowing exhaust gas 131. improves. Thereby, the disturbance of the swirling flow of the cooling air is reduced, and the air curtain can be maintained for a long time. As a result, the risk of coating occurrence is reduced.

  Further, the presence of the introduction wall 125 makes it difficult for the cooling air to leak out from the opening of the tip 123 of the tapered portion 124, and the introduced cooling air is efficiently used for protecting the inner walls of the cyclone 120 and the extraction pipe 128. It can be used to form an air curtain.

  If the expansion angle of the cement kiln exhaust gas introduction wall 125 with respect to the central axis of the cement kiln exhaust gas extraction processing device is α °, if α is excessively large, cooling air is blown out into the exhaust gas flow path and cooling efficiency decreases. Therefore, it is preferable that α is small. However, if α is excessively small, the length H of the bus bar of the cement kiln exhaust gas introduction wall 125 becomes long if the thickness of the introduction wall is constant. The introduction wall 125 is easily damaged by the collision. Therefore, 5 ° ≦ α ° ≦ 90−θ ° (however, θ ° ≦ 85 °) is preferable, and 10 ° ≦ α ° ≦ 90−θ ° (where θ ° ≦ 80 °) is preferable. More preferably, 20 ° ≦ α ° ≦ 90−θ ° (where θ ° ≦ 70 °) is even more preferable. Therefore, typically 5 ° ≦ α ° ≦ 70 °, and more typically 10 ° ≦ α ≦ 60 °.

  Moreover, the length H of the bus bar of the cement kiln exhaust gas introduction wall 125 may be adjusted as appropriate. However, if the bus bar is too short, the effect of blocking the upward flow of the cement kiln exhaust gas and drawing it into the cyclone 120 is reduced. While the sustainability improvement effect of the curtain is reduced, if the bus is too long, the introduction wall 125 may be damaged by the upward flow of cement kiln exhaust gas or collision of foreign matter, or the upward flow of exhaust gas flowing through the cement kiln exhaust gas flow path There is a concern that it may be an obstacle. The bus H is preferably in a relationship of 0.5 × D1 ≦ H, more preferably in a relationship of 0.8 × D1 ≦ H ≦ 5 × D1, and D1 ≦≦ the inner diameter D1 of the tip of the tapered portion 124. It is even more preferable that the relationship is H ≦ 3 × D1, and it is even more preferable that the relationship is D1 ≦ H ≦ 2 × D1.

  In addition, as shown in FIG. 2, it is preferable that the lowermost bus bar of the cement kiln exhaust gas introduction wall 125 is integrated with the inner wall of the cement kiln exhaust gas passage such as the rising duct 105. In this case, α = 90−θ. With such a configuration, the exhaust gas 131 flowing in the vicinity of the inner wall of the rising duct 105 flows smoothly into the cement kiln exhaust gas extraction processing apparatus 101. However, as shown in FIG. 7, the lowermost bus bar of the cement kiln exhaust gas introduction wall 125 may be configured to protrude inside the cement kiln exhaust gas passage such as the rising duct 105.

  In order to form a uniform swirling flow, the cooling air flow inlets 121 installed on the side surface of the body portion 122 of the cyclone 120 are open in a cylindrical shape or arranged at equal intervals in the circumferential direction. Is preferable. Further, referring to FIG. 3, in order to form a uniform swirl flow, a plurality of concentric circles surrounding the body portion 122 at locations where the introduction ports 121 are installed and arranged at equal intervals in the circumferential direction. A swirl strengthening unit 127 that houses swirl vanes 126 can be provided. Furthermore, it is preferable to make all the swirl vanes 126 with the same shape and size.

  Each swirl vane 126 is provided on the inner wall of the body portion so that the cooling air 130 can enter the body portion 122 through the inlet 121 and generate a swirl flow along the inner walls of the body portion 122 and the tapered portion 124. It is preferable to face the tangential direction or outward. In a preferred embodiment, each swirl vane 126 faces the outside by an angle β of 10 to 40 ° with respect to the tangential direction of the inner wall of the trunk portion 122 when the trunk portion 122 is observed from the central axis direction.

  A plurality of cooling air conveyance ducts 129 arranged in a substantially tangential direction of the cylindrical outer wall of the swirl strengthening unit 127 or arranged at equal intervals in the circumferential direction can be in fluid communication. In order to generate a stable swirl flow in the cyclone 120, it is preferable that a plurality of cooling air transport ducts 129 are arranged at equal intervals in the circumferential direction of the swirl strengthening unit 127. If the number of cooling air transport ducts 129 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, the number of the cooling air conveyance ducts 129 is preferably about 2, 3, or 4.

  The shape of the cyclone 120 is not particularly limited as long as it functions as a cyclone, but is exemplified below. In one embodiment of the cyclone 120 according to the present invention, the inner diameter D1 of the tip 123 of the tapered portion 124 and the inner diameter D2 of the body portion 122 satisfy the relationship D1 / D2 = 0.4 to 0.9. A smaller D1 / D2 is suitable for keeping the air curtain longer in the bleeder tube 128, but a smaller D1 / D2 results in a larger pressure loss and a larger energy required for the bleed. Since the place where the cooling air changes direction at the tapered portion tip 123 moves to the downstream side, the temperature at the tip 123 of the tapered portion tends to increase. Therefore, in view of the balance between the air curtain sustaining effect, the cooling effect in the cyclone 120, and the economy, it is preferable that the relationship of D1 / D2 = 0.7 to 0.8 is satisfied.

  On the other hand, if the insertion length L2 of the extraction pipe 128 is too short, it becomes difficult to generate a sufficient swirling flow on the inner wall of the extraction pipe 128. Is likely to occur. Therefore, in one embodiment of the cyclone 120 according to the present invention, the length L1 of the body portion 122, the insertion length L2 of the extraction tube 128, and the axial length L3 of the taper portion 124 satisfy L1 <L2 <L1 + L3. In a preferred embodiment, L1 <L2 <L1 + 0.5 × L3 is satisfied.

  In a typical embodiment of the cyclone 120 according to the present invention, the inner diameter D3 of the extraction tube 128 and the inner diameter D1 of the tip 123 of the tapered portion 124 satisfy D1 / D3 = 0.5 to 1.5. In a more typical embodiment, D1 / D3 = 0.6 to 1.3 is satisfied.

  It is desired that the cement kiln exhaust gas bleeder 101 is operated under conditions that can effectively suppress the occurrence of coating in the inside of the device, in particular, on the inner walls of the cyclone 120 and the bleed pipe 128. For this purpose, first, the cooling air having a flow rate sufficient to keep the temperature of the mixed gas of the cooling air 130 and the cement kiln exhaust gas 131 contacting the inner walls of the cyclone 120 and the extraction pipe 128 at 350 ° C. or less is introduced. Is desired. If the temperature of the mixed gas in contact with the inner wall of the cyclone 120 and the extraction pipe 128 is 350 ° C. or less, volatile components such as alkali chlorides and alkali sulfates are completely solidified into powder, Adhesion to the inner wall can be substantially prevented. As a result of sending the cooling air 130 having a sufficient flow rate into the cyclone, the cooling air 130 partially blows into the cement kiln exhaust gas flow path such as the rising duct 105 from the opening tip 123 of the tapered portion 124 of the cyclone 120. It doesn't matter.

  As described above, the cement kiln exhaust gas 131 that has flowed into the cyclone 120 is cooled by mixing with the cooling air 130, but in order to maintain a long air curtain due to the swirling flow even after the cooling air 130 changes direction. It is desirable that a strong swirl flow that is not easily destroyed by the cement kiln exhaust gas 131 is formed. Therefore, the flow rate of the cooling air 130 with respect to the flow rate of the cement kiln exhaust gas 131 is preferably 5 times or more in mass ratio, and more preferably 8 times or more. However, supplying cooling air more than necessary deteriorates the economic efficiency, and is typically 20 times or less, and may be 10 times or less.

  Hereinafter, the effect of the present invention is verified by a simulation using the thermal fluid analysis software SCRYU / Tetra manufactured by Cradle.

<Example 1 (comparison)>
When a cement kiln exhaust gas extraction apparatus without an introduction wall as shown in FIG. 4 was used, the temperature distribution of the gas flowing through the apparatus was examined by simulation. The structure and operating conditions of the cement kiln exhaust gas extraction treatment apparatus are as shown in Table 1.
The result of the simulation is schematically shown in FIG. As can be seen from FIG. 5, it can be seen that the isotherm of 350 ° C. greatly meanders in the extraction pipe, and high-temperature gas of 350 ° C. or higher is in contact with the extraction pipe. In such a situation, there is a high risk that a coating will be generated in the extraction pipe 128.

<Example 2 (Invention example)>
The temperature distribution of the gas flowing in the apparatus when the cement kiln exhaust gas extraction apparatus with the introduction wall attached to Example 1 as shown in FIG. 2 was examined by simulation. The structure and operating conditions of the cement kiln exhaust gas extraction treatment apparatus are as shown in Table 1. Here, the expansion angle α ° of the introduction wall is 50 °, and the length H of the busbar is 400 mm. Further, the lowermost part of the cement kiln exhaust gas introduction wall is integrated with the inner wall of the cement kiln exhaust gas flow path (that is, α ° = 90 ° −θ °).
The result of the simulation is schematically shown in FIG. As can be seen from FIG. 6, an isotherm of 350 ° C. exists almost symmetrically with respect to the central axis in the extraction tube, and the temperature of the gas contacting the inner walls of the cyclone 120 and the extraction tube 128 is 350 ° C. or less. I understand.

<Example 3 (Invention example)>
This is an example in which the temperature distribution of the gas flowing in the apparatus is simulated under the same conditions as in Example 2 except that the expansion angle α ° of the introduction wall is 40 ° and the length H of the busbar is 509 mm. Here, as shown in FIG. 7, the lowermost part of the cement kiln exhaust gas introduction wall is not integrated with the inner wall of the cement kiln exhaust gas passage, and the introduction wall protrudes entirely from the inner wall of the cement kiln exhaust gas passage. (Ie, α ° <90 ° −θ °).
The result was almost the same as in Example 2, but compared to Example 2, the downstream end of the 350 ° C. isotherm moved slightly upstream. Further, the temperature of the gas contacting the inner wall of the bleed pipe was also reduced as a whole compared to Example 2. Results are not shown.

<Example 4 (Invention)>
This is an example in which the temperature distribution of the gas flowing in the apparatus is simulated under the same conditions as in Example 2 except that the expansion angle α ° of the introduction wall is 30 ° and the length H of the busbar is 533 mm. Here, as shown in FIG. 7, the lowermost part of the cement kiln exhaust gas introduction wall is not integrated with the inner wall of the cement kiln exhaust gas passage, and the introduction wall protrudes entirely from the inner wall of the cement kiln exhaust gas passage. .
The result was almost the same as that in Example 3, but compared to Example 3, the downstream end of the 350 ° C. isotherm further moved to the upstream side. Further, the temperature of the gas contacting the inner wall of the bleed pipe was also reduced as a whole as compared with Example 3. Results are not shown.

<Example 5 (Invention)>
This is an example in which the temperature distribution of the gas flowing in the apparatus is simulated under the same conditions as in Example 2 except that the expansion angle α ° of the introduction wall is 20 ° and the length H of the bus bar is 691 mm. Here, as shown in FIG. 7, the lowermost part of the cement kiln exhaust gas introduction wall is not integrated with the inner wall of the cement kiln exhaust gas passage, and the introduction wall protrudes entirely from the inner wall of the cement kiln exhaust gas passage. .
The result was almost the same as in Example 4, but compared to Example 4, the downstream end of the 350 ° C. isotherm further moved to the upstream side. In addition, the temperature of the gas contacting the inner wall of the bleed pipe was also reduced as a whole compared to Example 4. Results are not shown.

<Example 6 (Invention)>
This is an example in which the temperature distribution of the gas flowing in the apparatus is simulated under the same conditions as in Example 2 except that the expansion angle α ° of the introduction wall is 10 ° and the length H of the busbar is 1,143 mm. Here, as shown in FIG. 7, the lowermost part of the cement kiln exhaust gas introduction wall is not integrated with the inner wall of the cement kiln exhaust gas passage, and the introduction wall protrudes entirely from the inner wall of the cement kiln exhaust gas passage. .
The result was almost the same as in Example 5, but compared to Example 5, the downstream end of the 350 ° C. isotherm moved further upstream. In addition, the temperature of the gas contacting the inner wall of the bleed pipe was also reduced as a whole compared to Example 5. Results are not shown.

(Discussion)
From Examples 2 to 6, it can be seen that, regardless of the expansion angle α °, 350 ° C. or less can be achieved in the cyclone and the bleed tube, which can suppress the formation of the coating. It can also be seen that the temperature of the gas flowing in the extraction pipe decreases as the spread angle α ° is decreased and the length H of the bus bar of the introduction wall is increased. This is considered to be due to the fact that the cooling air blown out into the cement kiln exhaust gas flow path decreased, and conversely the flow rate of the cooling air flowing through the cyclone and the extraction pipe increased and the cooling efficiency increased.

<Example 7 (Invention)>
In this example, the temperature distribution of the gas flowing in the apparatus is simulated under the same conditions as in Example 2 except that the inner diameter D1 of the tip 123 of the tapered portion 124 is halved compared to Example 2 and the length of the bus H is 533 mm. is there.
The results are shown in FIG. Unlike Examples 2-6, it turns out that the 350 degreeC isotherm is extended in parallel substantially downstream. This is considered to be due to the formation of a powerful air curtain by the cooling air. However, a portion exceeding 350 ° C. was observed at the opening tip of the tapered portion of the cyclone.

DESCRIPTION OF SYMBOLS 101 Cement kiln exhaust gas extraction processing apparatus 102 Rotary kiln 103 Preheater 104 Kiln inlet hood 105 Rising duct 106 Calcining furnace 107 Cyclone 108 Exhaust suction device 109 Dryer 110 Stabilizer 111 Electric dust collector 120 Cyclone 121 Cooling air inlet 122 Body part 123 Taper part Tip 124 of taper part 125 introduction wall 126 swirl vane 127 swirl strengthening unit 128 bleed pipe 130 cooling air 131 cement kiln exhaust gas

Claims (7)

A cement kiln exhaust gas extraction device that extracts a portion of cement kiln exhaust gas from a cement kiln exhaust gas flow path in which the cement kiln exhaust gas flows upward, mixes the extracted exhaust gas with cooling air, and lowers the exhaust gas temperature. ,
a) A cylindrical body having an inlet for introducing cooling air on its side surface, and a concentric shaft connected to the upstream side of the body, and the cooling air introduced from the inlet is swirled. A cyclone having a tapered portion for flowing toward the upstream side, wherein the tip of the tapered portion of the cyclone is in communication with the cement kiln exhaust gas flow path;
b) a bleed tube partially inserted concentrically from the downstream side toward the upstream side of the cyclone body; and c) concentrically connected to the upstream end of the tapered portion of the cyclone, and upstream. A reverse-tapered cement kiln exhaust gas introduction wall with an increasing inner diameter, wherein the cement kiln exhaust gas introduction wall is formed in the cement kiln exhaust gas passage;
However, the direction where the extracted cement kiln exhaust gas flows through the cement kiln exhaust gas extraction processing device is the downstream, and the opposite is the upstream,
Cement kiln exhaust gas extraction equipment with   The cement kiln exhaust gas extraction treatment apparatus according to claim 1, wherein the angle of the central axis of the cement kiln exhaust gas extraction processing device with respect to a horizontal plane is θ °, 20 ° ≤θ ° ≤70 °.   The cement kiln exhaust gas extraction treatment apparatus according to claim 2, wherein an expansion angle α ° of the cement kiln exhaust gas introduction wall with respect to the central axis of the cement kiln exhaust gas extraction processing device is 5 ° ≤α ° ≤90-θ °.   The cement kiln exhaust gas extraction processing apparatus according to claim 3, wherein α ° = 90−θ °.   The cement kiln exhaust gas extraction processing apparatus according to any one of claims 1 to 4, wherein the length H of the bus bar of the cement kiln exhaust gas introduction wall is larger than ½ of the inner diameter D1 of the tip of the tapered portion of the cyclone.   A method for operating a cement kiln exhaust gas extraction apparatus according to any one of claims 1 to 5, wherein the cooling air flows into the cyclone from the cooling air inlet of the body portion of the cyclone, and the cyclone. The cooling air that has flowed in progresses upstream while swirling the inner wall of the cyclone, changes direction at the tip of the tapered portion, and further proceeds downstream while swirling the inner wall of the bleed pipe. A part of the cement kiln exhaust gas flows from the kiln exhaust gas passage through the cement kiln exhaust gas introduction wall into the cyclone, and the cement kiln exhaust gas flowing into the cyclone is cooled by mixing with cooling air swirling around the process. The operation method including the process.   The operation method according to claim 6, wherein the temperature of the mixed gas of cooling air and cement kiln exhaust gas contacting the inner wall of the cyclone and the inner wall of the extraction pipe is maintained at 350 ° C. or lower.