JP2007044577A - Solid-gas separation method and apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid-gas separation method in which a dust-suspended gas containing the vapor of a substance to be solidified when cooled can suitably be separated separately into the substance to be contained therein and the dust while restraining the substance from being stuck to a solid-gas separation apparatus. <P>SOLUTION: The solid-gas separation method, which is used for separately separating the dust-suspended gas containing the vapor of the substance to be solidified when cooled into the substance and the dust, comprises the steps of: introducing the dust-suspended gas into a separating/cooling flow passage 2; introducing a cooling gas to be whirled almost around the central axis of the separating/cooling flow passage 2 into the separating/cooling flow passage 2 from an introduction line 3 connected to the separating/cooling flow passage 2; centrifugally separating the dust by a whirling current of the dust-suspended gas to be generated by the introduction of the cooling gas while cooling/solidifying the substance and while preventing the inner wall surface of the separating/cooling flow passage 2 from being brought into contact with the dust-suspended gas by the cooling gas; and separating the solidified substance. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a solid-gas separation method and apparatus for separating a substance and dust separately from a suspended gas containing the vapor of the substance that solidifies upon cooling and in which the dust is suspended, particularly in a kiln for producing cement clinker. The present invention relates to a solid-gas separation method and apparatus suitable for the treatment of the generated gas (hereinafter also referred to as kiln gas).

  Methods of recovering the substance from the suspended gas containing the vapor of the substance that solidifies when cooled and suspended in dust such as dust are roughly classified into the following two methods. .

  The first method is the method referred to below as a gas separation method, in which the substance is left in a vapor state at a high temperature, the dust is separated therefrom, and the suspended gas with reduced dust is cooled. This is a method of solidifying and collecting the substance. As long as the gas separation method can maintain a high temperature, for example, a normal solid-gas separation unit operation such as a cyclone can be used, and the design is easy.

  As a technique in which such a gas separation method is applied to kiln gas processing, for example, techniques described in Patent Documents 1 to 3 are known. However, these technologies have insufficient dust separation, or depending on the physical properties and operating conditions of volatile components mainly composed of potassium chloride and sodium chloride contained in the kiln gas, they are vaporized in the kiln. In the part lower than the kiln, there is a problem that deposits called “coaching” adhere to and grow on the part in contact with the kiln gas, which becomes an obstacle to the operation and prevents stable continuous operation.

  The second method is a method called a solid separation method, which will be described below. The suspended gas is cooled to solidify the substance, and a mixture of the solidified substance and the dust is used to obtain a difference in particle size and specific gravity. In general, separation is performed using a difference in physical properties such as solubility, and various effective unit operations have been proposed.

  As a technique in which such a solid separation method is applied to kiln gas processing, for example, a technique described in Patent Document 4 is known. However, in this technique, a considerable amount of the volatile components are strongly condensed and aggregated in the dust due to the cooling of the kiln gas, so that separation is difficult only by separation with a classifier, as in the technique described in Patent Document 5 Then, there is a problem that the separation process becomes complicated, such as requiring a water washing process thereafter.

JP 49-69758 A JP 54-54131 A Japanese Patent Laid-Open No. 9-301752 JP 63-210049 A JP 2003-286050 A

  The present invention has been made in view of the above problems, and separately contains the substance and the dust contained in the suspended gas containing the vapor of the substance that solidifies upon cooling and in which the dust is suspended. An object of the present invention is to provide a solid-gas separation method and apparatus that can be suitably separated while suppressing sticking to the apparatus.

  When handling the kiln gas of a cement kiln, the present inventors use the heat of the kiln gas to preheat the raw material, and observe in detail the coaching that grows in the preheater of the kiln with a suspension preheater. We found that growth is due to the following process.

(1) When the boiling point of the volatile component contained in the kiln gas is high, the high-temperature kiln gas is cooled by the ingress of the inner wall surface of the apparatus or outside air, and the volatile component is liquefied.
(2) The liquefied volatile component adheres to the inner wall surface of the apparatus as an adhering material together with cement raw material dust (hereinafter also simply referred to as dust) suspended in the kiln gas.
(3) The adhering matter adhering to the inner wall surface of the apparatus is cooled and solidified by a heat insulating effect accompanying its growth.
(4) The deposit has strength due to solidification, and the above (1) to (3) are repeated on the deposit, so that the deposit adheres and grows in layers, resulting in a thick coating.

  According to the above process, the growth of the coaching on the inner wall surface of the apparatus starts from the adhesion of the volatile component to the inner wall surface of the apparatus in the process of (2). Can be prevented.

  The inventors of the present invention have considered a method in which a curtain is made of another gas layer along the inner wall surface of the kiln gas flow path to protect the inner wall surface so that volatile components do not contact the inner wall surface. When making a curtain with this other gas, the swirl flow that brings about the curtain effect is introduced by introducing the gas from the tangential direction with respect to the outer periphery of the flow path so that the swirl flow is formed in the flow of the kiln gas. It has been found that it is sufficiently maintained downstream of the introduction position. As a result of further investigation, the following two findings were obtained and the present invention was completed.

  (1) By introducing another gas from the tangential direction of the outer periphery of the kiln gas flow path to form a swirling flow, the kiln gas also swirls, and coarse particles of dust suspended in the kiln gas Was centrifuged by a cyclone-like effect and moved to the wall of the channel. When it is not necessary to strictly separate the solidified volatile component and the dust in the kiln gas, the dust can be sufficiently separated and recovered.

  (2) Since the flow of the kiln gas is narrowed by the swirling flow of another gas, the upstream side of the other gas introduction part in the flow path of the kiln gas along the flow path wall surface by an action like an orifice. A reverse flow of another gas swirl flow occurred. Curtain effect is also applied to the inner surface of the kiln gas introduction part, which is a part where coaching is likely to occur, and it is possible to prevent coaching of that part without introducing a gas that causes the curtain effect to the part. This part can also be used for separation processing.

  The present invention has been made based on the above knowledge, and is a solid-gas separation method that separates the substance and the dust separately from a suspended gas containing the vapor of the substance that solidifies when cooled and in which the dust is suspended. The suspension gas is introduced into the separation cooling flow path, while the cooling gas swirling around the central axis of the separation cooling flow path as a substantially central axis is passed through the introduction passage connected to the separation cooling flow path. Introducing into the flow path, the cooling gas is solidified by cooling and solidifying the substance while preventing contact between the inner wall surface of the separation cooling flow path and the suspension gas, The present invention provides a solid-gas separation method in which the dust is centrifuged by a swirling flow of a suspended gas, and then the solidified substance is separated.

  The present invention is also a solid-gas separation apparatus for carrying out the solid-gas separation method of the present invention, wherein the suspension gas is introduced into a separation cooling channel and connected to the separation cooling channel. An introduction path for introducing a swirling flow of the cooling gas whose central axis is a substantially central axis in the separation cooling flow path, and the occurrence of the cooling gas that is provided on the wall of the separation cooling flow path and that is caused by the introduction of the cooling gas. A recovery means for recovering the dust centrifuged by the swirling flow of the suspension gas, and a separation means for separating the solidified substance disposed downstream of the recovery cooling flow path from the recovery means. A solid-gas separation device is provided.

  According to the solid-gas separation method and apparatus of the present invention, the substance and the dust contained in the suspended gas containing the vapor of the substance that solidifies when cooled and suspended in the dust are caused to adhere to the substance. It is possible to separate them suitably while suppressing them. In the present invention, in particular, the suspension gas is cooled and contained in the suspension gas while separating dust from the suspension gas by utilizing a large time scale difference between solid-gas separation and crystal growth at the time of solidification of volatile components. Since the solidifying substance is cooled, separation can be performed efficiently even in a small-scale apparatus.

  The present invention will be described below based on preferred embodiments with reference to the drawings.

  1 and 2 show a solid-gas separation device (hereinafter, also simply referred to as a separation device) of the present invention attached to a kiln gas flue 10 of a rotary kiln for producing cement clinker, and volatile components in the kiln gas (solidify when cooled). FIG. 1 schematically shows a first embodiment in which the present invention is applied to a separation apparatus that separates a substance) and dust (dust) from the kiln gas separately.

  As shown in FIG. 1, the separation device 1 of this embodiment includes a separation cooling channel 2 into which a kiln gas is introduced, and a central axis in the separation cooling channel 2 connected to the separation cooling channel 2. An introduction path 3 that introduces a swirling flow of cooling gas as an axis, a fan 4 that sends the cooling gas to the introduction path 3, and a wall portion of the separation cooling flow path 2 that is provided with the introduction of the cooling gas. The collecting means 5 for collecting the dust centrifuged by the swirling flow of the kiln gas, the cooling means 6 for cooling the gas discharged from the separation cooling flow path 2, and the gas solidified from the gas cooled by the cooling means 6 Separation means 7 for separating substances, a suction fan 8 for sucking gas from the kiln gas flue 10 to the separation means 7, and a gas discharged by the suction fan 8 are passed to the introduction path 3 via the fan 4. And a circulation path 9 for guiding.

  As shown in FIG. 2, the separation cooling flow path 2 is configured by a tube having a substantially circular cross section, and at both ends, the kiln gas introduction path 21 and the gas discharged after the separation cooling process is finished. A discharge path 22 is connected. The separation cooling channel 2 is preferably formed linearly, but may be bent or curved as long as the effect of the present invention is not affected.

  According to the examination results of the present inventors, in the separation cooling channel 2 during the treatment of the kiln gas, the temperature is set so as to form an annual ring-shaped isotherm from the inner wall surface of the separation cooling channel 2 toward the central axis. It was found that a distribution was formed, and the maximum temperature at the central portion of the cross section of the flow path decreased as it proceeded downstream of the separation cooling flow path 2. For this reason, the length of the separation cooling channel 2 is set to be longer than the length at which the processed gas is discharged at a position where the maximum temperature of the central portion is not higher than the freezing point of the volatile component contained in the kiln gas. It is preferable that the coating can be further prevented from occurring in the separation cooling channel 2.

  The introduction path 21 is preferably shorter in order to obtain a curtain effect due to the backflow of the cooling gas, which will be described later, and preferably has a length of about 2 times or less, particularly about 1 time or less, of the inner diameter of the separation cooling flow path 2. Moreover, the cross-sectional shape of the flow path can be elliptical.

  In the present embodiment, the separation cooling flow path 2 has a form in which the cross section of the flow path is gradually narrowed as it progresses downstream in the middle portion in the longitudinal direction. By adopting such a configuration for the separation cooling flow path 2, the separation cooling flow path on the upstream side from the position where the flow of the kiln gas is narrowed in combination with the flow of the kiln gas being narrowed to the central portion by the cooling gas as will be described later. The backflow of the cooling gas is generated in the inner wall portion of the two, and the backflow of the cooling gas prevents the contact between the kiln gas and the inner wall portion in the portion, thereby suppressing the occurrence of coaching. In order to effectively cause such a backflow, the sum of the cross-sectional area of the introduction path 21 and the cross-sectional area of the introduction path 3 on the downstream side after connection with the introduction path 3 is determined on the downstream side after connection with the introduction path 3. It is preferable that the cross-sectional area of the separation cooling flow path 2 is small and it is difficult for the cooling gas to easily flow backward.

  The end of the separation cooling channel 2 on the downstream side (connection side to the discharge channel 22) is configured to destroy the temperature distribution in the separation cooling channel as long as the curtain effect due to the introduction of the cooling gas is not impaired. It is preferable. In the present embodiment, the downstream end portion of the separation cooling channel 2 is provided so that the channel cross-section gradually spreads as it goes downstream. And in this part where the flow path cross section expanded, the discharge path 22 is connected so as to be double with the part and concentric with the separation cooling flow path before the flow path cross section is expanded. In this case, the channel cross section of the discharge channel 22 is preferably the same as the channel cross section of the separation cooling channel before the channel cross section is expanded. The method of connecting the discharge path 22 to the separation cooling flow path 2 (the diameter of the discharge path 22 and the overlapping state with the separation cooling flow path 2, that is, the degree of insertion into the separation cooling flow path 2) depends on the exhausted gas. Set in consideration of the properties of the dust contained.

  The introduction path 3 is connected so as to be in contact with the outer periphery of the flow path from the tangential direction on the considerably upstream side of the separation cooling flow path 2, and introduces the cooling gas in the tangential direction with respect to the flow of the kiln gas. A swirling flow of the cooling gas having the central axis of the flow path 2 as a substantially central axis is formed. The introduced cooling gas maintains a swirling flow along the inner wall surface of the separation cooling channel 2, and the cooling gas curtain protects the inner wall surface from contact with the high-temperature kiln gas.

  The swirling flow of the cooling gas formed in this manner generates a swirling flow also in the kiln gas that flows through the center portion thereof, so that cooling is performed while centrifugally separating dust in the outer circumferential direction of the separation cooling flow path 2 by the cyclone effect. To do.

  A work port 30 is provided in the introduction path 3, and the coaching attached to the inner wall portion is prevented from being blocked by the growth of the coaching so that the inlet portion of the introduction path 21 that introduces the kiln gas to the separation cooling flow path 2 is not blocked. It can be dropped from 30. In this working port 30, the cooling gas introduction path 3 is protected from the high temperature by the cooling gas, and because of the flow velocity of the cooling gas, the negative pressure is often lower than the surroundings according to Bernoulli's law. It is safe to prevent dust and coaching from adhering to the injection pipe from popping out, so you can work while driving. It is also preferable because it is close to the kiln gas introduction path 21 and can be easily operated.

  The introduction path 3 includes a gate as a flow rate adjusting means for adjusting the flow rate of the cooling gas. In the chlorine bypass of a kiln for producing cement clinker as in this embodiment, the amount of kiln gas may be changed within a range of about three times according to the amount of chlorine to be bypassed. In such a case, in order not to change the temperature of the exhaust gas discharged from the separation cooling channel 2, it is necessary to change the introduction amount of the cooling gas substantially in proportion to the amount of the kiln gas. In such a case, by adjusting the flow rate of the cooling gas at the gate, the flow rate of the cooling gas can be appropriately controlled even when the flow rate of the cooling gas is changed with the change of the flow rate of the kiln gas. .

  The recovery means 5 includes a hopper 50 that opens upward on the inner wall surface of the separation cooling channel 2. The dust separated in the outer peripheral direction of the separation cooling channel 2 by the swirling flow of the cooling gas is collected by this hopper. The opening area of the hopper 50 is set to a size within a range where the opening is not blocked by a lump of coating without impairing the effect of the cooling gas. In this case, in order to prevent the gas flow from being disturbed, the operation is performed in a state where dust is filled so as to fill the opening of the hopper by using the accumulation, and the inner wall surface of the separation cooling channel 2 is smoothed. It is preferable to maintain a curved shape. In order to collect more dust, the hopper 50 is preferably disposed in the vicinity of the discharge port of the separation cooling channel 2, but other positions, the vicinity of the downstream side of the cooling gas introduction portion, and the separation. It can also be disposed at a plurality of locations such as downstream of the cooling flow path 2.

  The cooling means 6 is not particularly limited as long as it cools the gas discharged from the separation cooling flow path 2 to the heat resistant temperature of the bag filter of the separation means 7. Although it is preferable to use a heat exchanger in order to suppress the gas throughput, it may be cooled by introducing a cooling gas such as air.

  Separation means 7 is composed of a dust collector equipped with a bag filter, and separates and collects solidified volatile components in the kiln gas solidified in the separation cooling flow path 2. As the dust collector, those conventionally used for the treatment of kiln gas are adopted.

  The circulation path 9 is a pipe line connecting between the exhaust port of the suction fan 8 and the intake port of the fan 4, and the exhaust gas from the suction fan 8 is used as a part or all of the cooling gas to connect the fan 4 and the introduction path 3. To the separation cooling channel 2 again.

  Next, an embodiment of the solid-gas separation method of the present invention will be described based on an embodiment using the solid-gas separation device 1.

  First, a part of the kiln gas is introduced from the kiln into the separation cooling flow path 2 through the introduction path 21. The kiln gas introduced from the kiln is a high-temperature gas of about 900 to 1300 ° C., and is a suspended gas in a state where dust is suspended while containing vapor mainly composed of potassium chloride and sodium chloride as volatile components. .

  It is preferable to add a gas adsorbent coolant to the kiln gas introduced into the separation cooling channel 2. By adding such a coolant, the cooling effect of the kiln gas can be obtained, and the sulfurous acid gas contained in the kiln gas can be adsorbed to increase the acid dew point, so that the corrosion prevention effect of the apparatus can also be obtained. . For the chemical adsorption of sulfurous acid gas, considering the reaction rate, a temperature of about 800 ° C. is suitable, and it is preferable to add in a region where the temperature of the kiln gas becomes such a temperature. Examples of such a gas adsorbing coolant include dust having a relatively small particle diameter, cement raw material, limestone powder and the like collected by a collecting means as described later. The amount of the coolant added can be set according to the temperature of the discharge passage 22 and the sulfurous acid gas concentration.

  While a part of the kiln gas is introduced into the separation cooling channel 2 as described above, the cooling gas swirling around the central axis of the separation cooling channel 2 by the fan 4 is passed through the introduction channel 3 by the fan 4. 2 is introduced. Air is preferably used as the cooling gas. The temperature of the cooling gas only needs to be a temperature at which a cooling effect capable of solidifying the volatile components in the kiln gas is obtained, but considering the dew point of the volatile components and generated components accompanying the cooling, and the heat resistance of the flow path, 100-350 degreeC is preferable and 150-200 degreeC is more preferable. Using part or all of the cooling gas as the exhaust gas from the separation means 7 is preferable in that the amount of gas related to the treatment can be reduced and the sulfurous acid gas can be recovered as gypsum and used as a cement raw material.

  Subsequently, the cooling gas introduced into the separation cooling channel 2 is cooled and solidified while the volatile component is cooled and solidified while preventing contact between the inner wall surface of the separation cooling channel 2 and the kiln gas. The dust is centrifuged by the swirling flow of the kiln gas generated along with the introduction, and recovered by the recovery means 5.

  That is, in the separation cooling channel 2 in which the above-described temperature distribution is formed, the kiln gas and the cooling gas are gradually mixed in layers from the periphery of the channel to the center in 0.3 to 3 seconds. The And by the cooling of the kiln gas accompanying mixing with this cooling gas, the said volatile component is rapidly cooled and solidified, and it becomes a fine particle fume. In other words, compared to the time scale of 0.1 to 1 second or less in the solid-gas separation method using centrifugal force, the mixture is gradually mixed, and the crystal growth time scale at the time of solidification of volatile components (fume rather than initial production) (It usually takes a few seconds to a few minutes, or even an hour or more), because the volatile components are cooled rapidly. The fumes of the volatile components are fine particles that are hardly affected by the centrifugal force due to the swirling flow generated with the introduction of the cooling gas, and are not separated in the separation cooling flow path 2 without being centrifuged. It is sent downstream by the kiln gas flow in the center. On the other hand, the dust is moved in the outer peripheral direction of the separation cooling flow path 2 by the action of the centrifugal force generated by the swirling flow generated with the introduction of the cooling gas, and is recovered by the recovery means 5.

  The degree to which dust is separated by the centrifugal separation can be qualitatively considered in accordance with an equation for obtaining a critical particle size when a cyclone is designed. The dimension corresponding to the inner diameter of the separation cooling flow path 2 (for example, the inner diameter of the separation cooling flow path 2 when the flow passage section of the separation cooling flow path 2 is a circle) is reduced, or the length in the axial direction is increased. If the introduction rate of the cooling gas is increased, even finer dust can be separated and recovered. Due to the turbulence of gas and the movement of particles, the lower limit of the particle size of dust that can be separated and recovered by applying such centrifugal force is practically about 5 to 10 μm in many cases.

  The particle size of the cement raw material corresponding to the dust contained in the kiln gas is approximately 2 to 100 μm (90% or more), but due to aggregation, the particle size evaluated by the cyclone dust collection mechanism is approximately 10 to 50 μm. Distributed. That is, the suspension preheater, which is a cement raw material preheating device, is configured so that particles collected by the cyclone are supplied to the lower stage and finally become a kiln raw material, so that the kiln gas introduced from the introduction passage 21 is used. The dust that is the raw material of the kiln is mainly composed of such aggregated particles. Therefore, in the present embodiment, the dust contained in the kiln gas can be roughly separated and recovered by applying the centrifugal force.

  The recovered dust is preferably reused. The recovered dust has a particle size that varies depending on the location of the hopper, and has a particle size of approximately 30 μm or more recovered in the vicinity of the downstream side of the cooling gas introduction portion. Since there are those that are included and those with a particle size of about several μm to 100 μm that are recovered downstream of the separation cooling channel, a plurality of recovery means 5 can be provided. It is preferable that dust having a relatively large particle size like the former is re-introduced into the kiln in consideration of ease of processing. When the collected dust is reintroduced into the kiln, it is preferable to attach a chute with no special refractory construction to the bottom cyclone chute of the suspension preheater or the kiln outlet duct through which the kiln raw material to be introduced into the kiln flows. . It is more preferable to attach an insertion damper, a rotary feeder, and a screw conveyor in order to adjust the input amount and ensure airtightness, and it is preferable to perform refractory construction in a portion where the temperature is high. Moreover, you may return to the feed raw material and compounded raw material of a suspension preheater. On the other hand, the dust with relatively fine particle size, like the latter, contains about half of the slaked lime, and part of it is gypsum and calcium sulfide, so the whole or part of it can be added to the clinker or cement. The elution of trace components of cement can be suppressed by the effect of calcium sulfide. Moreover, you may collect | recover and process with the solidified material of the said volatile component isolate | separated and collect | recovered by the isolation | separation means 7. FIG. Moreover, since the reaction with the sulfurous acid gas in the kiln gas is promoted by circulating and using as the coolant, it can be more suitably used when added to cement as a substitute for gypsum. Furthermore, it can be re-entered into the kiln as in the former case.

  In this embodiment, due to the orifice effect generated by narrowing the flow of the kiln gas with the cooling gas introduced into the separation cooling flow path 2 via the introduction path 3, the cooling gas in the direction opposite to the flow of the kiln gas is reduced. A flow is formed. This flow prevents contact between the inner wall surface of the upstream portion of the separation cooling flow channel 2 and the kiln gas from the cooling gas introduction portion, thereby preventing the occurrence of coaching in the inner wall surface portion. Can do.

  Considering the dew point of sulfurous acid gas contained in the kiln gas and the melting point of the volatile component, the temperature of the exhaust gas discharged from the separation cooling channel 2 is preferably 130 to 500 ° C.

  Thereafter, the exhaust gas is cooled below the heat resistant temperature of the bag filter, and the solidified volatile components are separated and collected by the bag filter.

  In this embodiment, exhaust gas discharged from the suction fan 8 is introduced into the separation cooling flow path 2 via the suction fan 8, the circulation path 9, the fan 4 and the introduction path 3 as all or part of the cooling gas. To do. This is preferable because the gas throughput can be reduced.

  According to the solid-gas separation device 1 of the present embodiment described above and the solid-gas separation method using the same, the volatile components and dust contained in the kiln gas are suitably suppressed while suppressing the fixation of the volatile components to the device. Can be separated. In particular, in this embodiment, a large difference in time scale between solid-gas separation and crystal growth during solidification of volatile components is utilized, and the kiln gas is cooled while the dust is separated from the kiln gas to cool the volatile components contained therein. Therefore, separation can be performed efficiently even with a small-scale apparatus.

  FIG. 3 shows the result of calculating the temperature distribution and the dust flow in the solid-gas separation flow path by computer simulation as follows in the implementation of the present invention. In the calculation, a separation cooling path having a narrowed end on the introduction path side as shown in FIG. 3 was used, and the hopper of the recovery means was omitted. Also, in order to perform the calculation in a short time, when the gas is pushed in evenly from the end on the introduction path side, the effect appears greatly at the entrance of the introduction path. It was dealt with by considering it as an unimportant part. In addition, the interaction between the particles included in the gas was ignored.

<Temperature distribution>
1100 ° C gas (carbon dioxide 25%, oxygen 3%, water vapor 8%, nitrogen 64%) was blown in at a rate of 2.4 m / sec from the introduction channel side, and 30 ° C air was cooled from the cooling gas introduction channel. It was calculated by blowing in as gas at 7.8 m / sec. The result is shown in FIG.

<Dust flow>
In the case where 128 spherical particles having a density of 2000 kg / m ³ are blown from the position where 32 spherical particles in the cross section on the introduction path side and 4 in the radial direction are evenly distributed in the base gas, 3 μm, 10 μm In addition, the calculation was performed by ignoring the interaction between the particles for three particle sizes of 30 μm. The result is shown in FIG.

  As shown in FIG. 3, at the end of the separation cooling channel on the discharge side, the gas temperature is lowered to 500 ° C. or less even in the center, and the inner wall surface on the introduction side is also protected by the backflow of the cooling gas. It was. In addition, as shown in FIGS. 4A to 4C, it was found that particles having a size of 10 μm or more are almost on the wall surface.

  In actual design, it is necessary to carry out a strict calculation with a more detailed model. However, even if a hopper 50 as shown in FIG. 2 is connected to the above model as a recovery means, the melting point of the volatile component contained in the kiln gas is substantially reduced. Since it is 600 ° C. or higher, no coating is generated on the inner wall surface of the separation cooling channel or the discharge channel, and particles of 10 μm or more (more specifically about 8 μm or more) are caused by the centrifugal separation action by introducing the cooling gas. It was calculated that it could be recovered. Further, based on the result of such a simulation, it is possible to set operating conditions such as the internal detailed shape and the speed of the suspended gas and the cooling gas.

The present invention is not limited to the embodiment.
For example, it may be discharged without being circulated in the circulation path 9. Since the exhaust gas contains sulfurous acid gas and the like, it is necessary to discharge after processing, and it is preferable to return the exhaust gas to the cement clinker production process for processing.

  In the above embodiment, one cooling gas introduction path 3 is provided, but a plurality of introduction paths may be provided. It is preferable to provide a plurality of introduction paths 3 because the kiln gas can easily flow through the central portion of the separation cooling flow path 2, so that dust separation and backflow of the gas can be easily generated cleanly.

  In addition, when the introduction path 21 has to be set longer by design and the backflow effect of the cooling gas cannot be sufficiently expected, a new cooling gas can be introduced from the introduction port of the introduction path 21. Also in this case, it is preferable to introduce the cooling gas from the tangential direction with respect to the outer periphery so that the kiln gas is swirled as in the cooling gas introduction path 3 in the separation cooling flow path 2.

  Further, the cooling gas introduction path 3 is also connected to the kiln gas introduction path 21 to the separation cooling flow path 2 so that the adhesion of the coating to the introduction path 21 can be prevented by the cooling gas introduced from the introduction path. You can also As the cooling gas, the same gas as that used for the introduction path 3 in the above embodiment can be used. Thus, by introducing the cooling gas separately from the separation cooling flow path 2, it is effective even when the distance of the introduction path 21 is long and the effect of preventing the adhesion of the coating due to the back flow of the cooling gas cannot be obtained sufficiently. Coaching adhesion can be prevented.

  Further, in order to make the backflow of the cooling gas from the introduction path 3 easier to occur, a structure in which the flow path of the separation cooling flow path 2 is narrowed from the center by the cooling gas is preferable. For this purpose, for example, in FIG. 1 and FIG. 2, the separation cooling flow path 2 has its inner diameter expanded before and after the connecting portion with the introduction path 3, but the inner diameter of the introduction path 21 is not expanded as such. Is preferably kept the same.

  Further, within the range not impairing the effect of the present invention, it is effective to provide a baffle plate or a weir at the inlet of the kiln gas introduction passage 21 to restrict the flow path from the outer periphery in order to cause a backflow of the cooling gas.

[Example 1]
When the device shown in FIG. 1 is used and the solid-gas separation treatment of the kiln gas is performed without circulating the exhaust gas and adding the coolant, the dust recovered by the centrifugal separation in the separation cooling flow path is Compared to the raw material collected by the bottom cyclone, which is the kiln raw material, approximately 2.5% more chlorine and potassium were obtained, and almost the same dust was recovered except SO ₄ was about 5% more. On the other hand, as a result of chemical analysis of the recovered material separated and recovered by the separation means, the recovered material contains 50% potassium chloride, 5% sodium chloride and 10% potassium sulfide, and the compound is unknown, but lead, Cadmium and selenium were also included in a total of about 1%. The remaining part is mainly the above-described kiln raw material, but it contains about 5% more SO _{4 and} more Al ₂ O ₃ than that. This result was presumed to be because a larger amount of fine components of the kiln raw material that was not centrifuged in the separation cooling channel was recovered. From this result, the recovered material is about 30% of dust containing a large amount of fine particles, about 60% of solidified volatile components, and about 10 of the chemical adsorbed (reacted) sulfurous acid gas contained in the gas. %. Similarly, the recovered material recovered by the centrifugal separation operation was estimated to be about 85% dust, about 10% solidified volatile components, and about 5% sulfurous acid gas.

[Comparative Example 1]
An operation was performed in which the hopper of the recovery means was filled with the recovered material, and the entire amount was separated and recovered by the separating means without recovering the recovered material. As a result of chemical analysis in the same manner as in Example 1, the recovered material by the separation means at this time was estimated to be about 70% dust, about 25% solidified volatile components, and about 10% chemically adsorbed sulfurous acid gas. . Although various mechanical classifications of this recovered material were attempted using a sieve, a separator, etc., the solidified product of volatile components increased only to about 35% at the maximum. The reason for this is thought to be that the entire amount was recovered as the recovered material of the distribution means, and the solidified volatile components, which are mostly fine particles, strongly aggregated into the coarse particles contained in the recovered material.

  Therefore, using data obtained when a solid-gas separation device equipped with a cyclone conventionally used in a solid separation method as a classifier is applied to a chlorine bypass of a kiln for producing a cement clinker, Example 1 and Comparative Example The result of 1 was examined as follows.

That is, when the concentration of the solidified product of the volatile component in the collected material by the conventional solid-gas separation device was about 60%, which was the same as in Example 1, the volatile content in the collected material collected by the classifier was examined. The concentration of the solidified component was about 17%. Here, the ratio (recovery rate) collected as a recovered product in the separation means of a certain component of interest is obtained. Regarding the component of interest, when the recovered material by the classifier of concentration N1 and the recovered material by the separation means of concentration N2 are mixed at a: (1-a), the concentration N is the concentration when the above-mentioned total amount is separated and recovered by the separating means. If you think
aN1 + (1-a) N2 = N
It is. Solving this equation
a = (N-N2) / (N1-N2)
Is obtained. Therefore, the recovery rate is
(1-a) N2 / N = (1-N1 / N) / (1-N1 / N2)
It becomes.

When paying attention to the concentration of the solidified product of the volatile component and calculating the recovery rate of the solidified product,
Example 1 is (1-10 / 25) / (1-10 / 60) = 72%
Comparative Example 1 is (1-17 / 25) / (1-17 / 60) = 45%
Met.

  The method according to Comparative Example 1 is a solid separation method. If only the fine powder side that has not been agglomerated is separated and recovered as a recovered material by the separating means, it is possible to exert the same level of separation ability as in Example 1. Because of solidification and agglomeration, solidified products of many volatile components are inevitably contained on the coarse powder side, which is inefficient from the viewpoint of recovery of only the solidified products. In this regard, according to the present invention, it was found that the recovery efficiency is high if the concentration is approximately the same.

  The solid-gas separation method and apparatus of the present invention is suitable for the treatment of kiln gas in a kiln for producing cement clinker as in the above embodiment, but can also be applied to, for example, exhaust gas treatment in a garbage incinerator. In addition, chlorides such as vaporous salt and heavy metals contained in exhaust gas and fine powder contained in garbage can be separated separately, and an effect of suppressing the production of dioxins by rapid cooling can be expected.

It is a figure which shows typically one Embodiment of the solid-gas separation apparatus of this invention. It is an enlarged view which shows the principal part of FIG. 1 typically, (a) is a longitudinal cross-sectional view (AA sectional drawing of (b)) of the junction part of the introduction path | route of a cooling gas, (b) is a separated cooling flow. The figure which looked at the path | route from the downstream, (c) is a figure which shows the positional relationship of a discharge path and a collection | recovery means. It is a figure which shows the result of having calculated the outline of the temperature distribution in the separation cooling flow path in this invention by computer simulation. (A)-(c) is a perspective view which shows the result of having calculated the flow of the dust in the suspension gas which flows through the inside of the separation cooling flow path in this invention for every particle size by computer simulation.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Solid-gas separation apparatus 2 Separation cooling flow path 3 Introductory path 4 Fan 5 Recovery means 6 Cooling means 7 Separation means 8 Suction fan 9 Circulation path 10 Kiln gas flue 11 Chlorine bypass

Claims (8)

A solid-gas separation method for separately separating the substance and the dust from a suspended gas containing the vapor of the substance that solidifies upon cooling and in which the dust is suspended,
The suspension gas is introduced into the separation cooling channel, and the cooling gas swirling around the central axis of the separation cooling channel is passed through the introduction channel connected to the separation cooling channel. The suspension generated by the introduction of the cooling gas while being cooled and solidified while preventing the contact between the inner wall surface of the separation cooling channel and the suspension gas with the cooling gas. A solid-gas separation method in which the dust is centrifuged by a swirling gas flow, and then the solidified substance is separated.   The solid-gas separation method according to claim 1, wherein the flow of the suspension gas is narrowed by the cooling gas introduced into the separation cooling flow path to form the flow of the cooling gas in a direction opposite to the flow of the suspension gas. .   The solid-gas separation method according to claim 1 or 2, wherein the suspended gas from which the dust and the substance are separated is introduced into the separation cooling channel as all or part of the cooling gas.   The solid-gas separation method according to claim 1, wherein a gas adsorbing coolant is added to the suspension gas.   The solid-gas separation method according to any one of claims 1 to 4, wherein the suspended gas is a gas derived from a kiln for producing a cement clinker. A solid-gas separation device for carrying out the solid-gas separation method according to claim 1,
A separation cooling channel into which the suspended gas is introduced, and an introduction channel that is connected to the separation cooling channel and introduces a swirling flow of the cooling gas with the central axis as a substantially central axis in the separation cooling channel. A recovery means for recovering the dust centrifugally separated by a swirling flow of the suspension gas that is provided on the wall of the separation cooling flow path and that is generated by the introduction of the cooling gas; and the separation cooling by the recovery means A solid-gas separation device comprising: a separation unit that is disposed downstream of the flow path and separates the solidified substance.   The solid-gas separation device according to claim 6, wherein a flow path cross section of the separation cooling flow path is narrowed downstream from a connection position of the introduction path. The solid-gas separation device according to claim 6 or 7, further comprising a circulation path for guiding the gas discharged from the separation means to the introduction path.

Images