Method for operating clinker cooler, method for producing cement clinker, and apparatus for producing cement clinker

Abstract

To provide an apparatus for producing cement clinker that enables stable production of cement clinker.SOLUTION: Provided is an apparatus for producing cement clinker, comprising a kiln 14 for firing a cement raw material to yield a fired product, and a clinker cooler 16 for cooling the fired product while conveying it to produce cement clinker, wherein the clinker cooler 16 is provided with a spray nozzle 25 for spraying water droplets 42 into its interior, and the water droplets 42 are fully vaporized prior to arrival at the rear-end region of a conveying section 20 that conveys the clinker cooler 16.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a method for operating a clinker cooler, a method for producing cement clinker, and an apparatus for producing cement clinker. [Background technology]

[0002] In the sintered ore manufacturing process, a technique is known in which a mist spray nozzle is provided in the device. For example, Patent Document 1 discloses a technique for cooling sintered ore moving downward in a chute connected to a cooler using a mist spray nozzle having a dispersion type nozzle shape capable of forming mist particles of less than 1000 microns. Patent Document 2 discloses a technique for causing fine ore contained in the exhaust gas to settle and adhere to the sintered ore product by spraying a two-layer fluid of water and air onto dust-containing exhaust gas rising through a sintered ore layer in a sintered ore cooler pan. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-85303 A [Patent Document 2] Japanese Patent Application Publication No. 7-167565 Summary of the Invention [Problem to be solved by the invention]

[0004] When water droplets are sprayed into a clinker cooler, if the droplets are large or the flow rate of the exhaust gas in the clinker cooler is high, the moisture cannot be sufficiently evaporated in the clinker cooler. Such water droplets circulate while carrying dust in the exhaust gas, and collide with refractories and the like downstream of the clinker cooler, causing coating. In this respect, the present disclosure provides a method for operating a clinker cooler that can suppress the occurrence of coating in the clinker cooler. In addition, the present disclosure provides a method for producing cement clinker and a cement clinker production device that can stably produce cement clinker by performing such a method for operating a clinker cooler. [Means for solving the problem]

[0005] One aspect of the present disclosure provides the following clinker cooler operation methods [1] to [6].

[0006] [1] A method for operating a clinker cooler that cools a burned cement raw material while transporting it, comprising the steps of: spraying water droplets into the interior of the clinker cooler; The method for operating a clinker cooler, wherein the water droplets are all vaporized by the time they reach a rear end region of a conveying section that conveys the burnt material in the clinker cooler. [2] A method for operating a clinker cooler as described in [1], comprising a step of introducing exhaust gas from the clinker cooler, which contains at least a portion of the water vapor gas produced by evaporation of the water droplets, into an electric dust collector to recover dust. [3] The method for operating a clinker cooler according to [2], wherein the temperature of the flue gas when introduced into the electric dust collector is maintained at 400°C or lower. [4] A method for operating a clinker cooler according to [2] or [3], comprising a step of adjusting the amount of water droplets sprayed based on a measured value of the temperature of the flue gas when it is introduced into the electric dust collector. [5] The clinker cooler is provided with a curtain chain downstream of the spray nozzle that sprays the water droplets, The method for operating a clinker cooler according to any one of [1] to [4], wherein the water droplets are all vaporized by the time they reach the curtain chain. [6] The method for operating a clinker cooler according to any one of [1] to [5], wherein the spray nozzle for spraying the water droplets sprays water droplets having a droplet diameter of 160 μm or less.

[0007] In the above-mentioned operation methods [1] to [6], in the step of spraying water droplets inside the clinker cooler, the water droplets are sprayed so that they are all vaporized before reaching the rear end of the conveying section that conveys the burnt material. Therefore, the frequency of collision of water droplets with refractories and the like downstream of the clinker cooler can be reduced, and coating can be suppressed. In the above-mentioned operation method [2], since exhaust gas containing at least a part of the water vapor gas generated by vaporization of water droplets is introduced into the electric dust collector, the performance of the electric dust collector can be fully exhibited, and the dust in the exhaust gas can be fully captured. According to the above-mentioned operation methods [3] and [4], the performance of the electric dust collector can be fully exhibited, and the dust in the exhaust gas can be fully captured. According to the above-mentioned operation method [5], coating can be fully suppressed even when a curtain chain is provided. According to the above-mentioned operation method [6], coating in the clinker cooler can be fully suppressed.

[0008] One aspect of the present disclosure provides a method for producing cement clinker as described below in [7].

[0009] [7] A method for producing cement clinker, comprising: a step of burning cement raw materials in a kiln to obtain a burned product; and a step of cooling the burned product in a clinker cooler to obtain cement clinker, A method for producing cement clinker, comprising operating the clinker cooler according to any one of the clinker cooler operating methods described in [1] to [6].

[0010] In the manufacturing method [7] above, in the step of spraying water droplets inside the clinker cooler, the water droplets are sprayed so that they are all vaporized by the time they reach the rear end of the transport section that transports the burnt material. This reduces the frequency of water droplets colliding with refractories and the like downstream of the clinker cooler, thereby suppressing coating.

[0011] One aspect of the present disclosure provides the following cement clinker production apparatuses [8] to

[13] .

[0012] [8] A cement clinker manufacturing apparatus comprising: a kiln for burning cement raw materials to obtain a burned product; and a clinker cooler for cooling the burned product while transporting it to obtain cement clinker, The clinker cooler is provided with a spray nozzle for spraying water droplets therein, The cement clinker manufacturing apparatus, wherein the water droplets are all vaporized by the time they reach a rear end region of a conveying section that conveys the clinker cooler. [9] A method for producing a clinker cooler comprising the steps of: The cement clinker manufacturing apparatus according to [8], wherein the exhaust gas introduced into the electric dust collector contains at least a portion of the water vapor gas produced by vaporization of the water droplets.

[10] The cement clinker manufacturing apparatus according to [9], configured to maintain the temperature of the exhaust gas at 400°C or lower when introduced into the electric dust collector.

[11] A temperature measuring unit that measures the temperature of the exhaust gas when it is introduced into the electric dust collector; A control unit that adjusts the amount of water droplets sprayed from the spray nozzle based on the measured value measured by the temperature measuring unit.

[12] the clinker cooler includes a curtain chain downstream of the spray nozzle; The cement clinker manufacturing apparatus according to any one of [8] to

[11] , wherein the water droplets are all vaporized before reaching the curtain chain.

[13] The apparatus for producing cement clinker described in any one of [8] to

[12] , wherein the spray nozzle is configured to spray the water droplets having a droplet diameter of 160 μm or less.

[0013] In the manufacturing apparatuses [8] to

[13] above, a spray nozzle for spraying water droplets onto the clinker cooler is provided, and the water droplets are all vaporized before reaching the rear end region of the conveying section that conveys the clinker cooler. Therefore, the frequency of collision of water droplets with refractories and the like downstream of the clinker cooler can be reduced, and coating can be suppressed. In the manufacturing apparatus [9] above, the flue gas introduced into the electric dust collector contains at least a part of the water vapor gas generated by the vaporization of water droplets, so that the performance of the electric dust collector can be fully exhibited, and the dust in the flue gas can be fully captured. According to the manufacturing apparatuses

[10] and

[11] above, the performance of the electric dust collector can be fully exhibited, and the dust in the flue gas can be fully captured. According to the manufacturing apparatus

[12] above, coating can be fully suppressed even when a curtain chain is provided. According to the manufacturing apparatus

[13] above, coating in the clinker cooler can be fully suppressed. Effect of the Invention

[0014] According to the present disclosure, it is possible to provide a method for operating a clinker cooler that can suppress the occurrence of coating in the clinker cooler. In addition, it is possible to provide a method for producing cement clinker and an apparatus for producing cement clinker that can stably produce cement clinker by performing the above-mentioned method for operating a clinker cooler. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a diagram showing an example of a cement clinker production apparatus. [Diagram 2] FIG. 2 is a diagram illustrating an example of an operating state of a clinker cooler. [Diagram 3] FIG. 3 is a side view illustrating an example of the conveying unit. [Figure 4]4(A) and 4(B) are top views showing examples of a grate provided in the transport section. [Diagram 5] FIG. 5 is a flowchart illustrating an example of a series of processes executed by the control unit. [Figure 6] FIG. 6 is a graph showing the change over time in the temperature of the exhaust gas when it is introduced into the electrostatic precipitator of Comparative Example 1 and Example 1, and the dust concentration in the exhaust gas discharged from the electrostatic precipitator. [Figure 7] Fig. 7(A) is a photograph taken inside the clinker cooler before the start of operation in Example 1. Fig. 7(B) is a photograph taken at the same location after two months of operation in Example 1. [Figure 8] 8(A) and (B) are photographs taken inside the clinker cooler in Comparative Example 2 after two months of operation. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings as needed. However, the following embodiment is an example for explaining the present disclosure, and is not intended to limit the present disclosure to the following content. In the description, the same reference numerals are used for the same elements or elements having the same functions, and redundant description is omitted as the case may be. In addition, the positional relationship such as up, down, left, right, etc. is based on the orientation of the reference numerals in the drawings unless otherwise specified. The dimensional ratio of each element is not limited to the ratio shown in the drawings. In addition, a numerical range between an upper limit value and a lower limit value indicated by "~" is a numerical range including the upper limit value and the lower limit value.

[0017] A method for operating a clinker cooler according to one embodiment is a method for operating a clinker cooler that cools burned cement raw material while transporting it, and includes a step of spraying water droplets into the inside of the clinker cooler, and the water droplets are sprayed so that they are all vaporized before they reach the rear end region of the transport section that transports the burned material in the clinker cooler. The water droplets may be sprayed from a spray nozzle. There may be one or more spray nozzles. The position at which the sprayed water droplets are all vaporized varies depending on factors such as the droplet size (diameter) of the water droplets sprayed from the spray nozzle, the amount and position of spraying, the temperature of the exhaust gas at that position, and the flow rate of the exhaust gas flowing through the clinker cooler.

[0018] The sprayed water droplets are all vaporized before reaching the rear end region of the conveying section, so that coating on the inner walls of the clinker cooler can be suppressed. Coating is a phenomenon in which dust in the exhaust gas adheres to the wall. When coating occurs, it becomes necessary to open the clinker cooler and remove the coating. If coating can be suppressed, the frequency of clinker cooler shutdowns can be reduced, and the clinker cooler can be operated stably for a long period of time.

[0019] A method for producing cement clinker according to one embodiment includes a step of burning cement raw materials in a kiln to obtain a burned product, and a step of cooling the burned product in a clinker cooler to obtain cement clinker, and the clinker cooler is operated by the above-mentioned operating method. This production method also suppresses the occurrence of coating on the inner wall of the clinker cooler, and the clinker cooler can be operated stably for a long period of time. Therefore, cement clinker can be produced stably for a long period of time.

[0020] An apparatus for manufacturing cement clinker according to one embodiment includes a kiln for calcining cement raw materials to obtain a calcined product, and a clinker cooler for cooling the calcined product while transporting it to obtain cement clinker. The clinker cooler is provided with a spray nozzle for spraying water droplets into the interior thereof, and the spray nozzle sprays the water droplets so that all of the water droplets are vaporized by the time they reach the rear end region of the transport section that transports the clinker cooler. By spraying the water droplets, it is possible to promote cooling of the exhaust gas and the calcined product in the clinker cooler.

[0021] The cement production apparatus can be used to carry out the above-mentioned method for operating a clinker cooler and method for producing cement clinker. The following describes the common features of the method for operating a clinker cooler, the method for producing cement clinker, and the cement clinker production apparatus.

[0022] Examples of cement raw materials include limestone, but raw materials other than limestone may also be used. In the kiln, the cement raw materials are fired to produce a fired product consisting of cement clinker. This fired product is usually also called cement clinker, but in this disclosure, the fired product before being cooled in the clinker cooler is called the "fired product." In addition, the "fired product" cooled in the clinker cooler is called the "cement clinker."

[0023] In the clinker cooler, the burnt material is cooled by cooling air and, if necessary, pulverized to produce cement clinker. In the clinker cooler, high-temperature exhaust gas is generated when the air comes into contact with the burnt material. The exhaust gas is accompanied by dust (fine particles) that was contained in the burnt material. If moisture is present, this dust forms a coating mainly on the inner wall downstream of the clinker cooler. In this embodiment, all water droplets are evaporated before reaching the rear end region of the conveying section, so the formation of such a coating can be suppressed. In this disclosure, the terms "upstream" and "downstream" are used based on the direction in which the burnt material is conveyed.

[0024] The dust may be entrained in the exhaust gas containing water vapor gas and discharged from the clinker cooler. The exhaust gas containing dust and water vapor discharged from the clinker cooler may be introduced into an electric dust collector to collect the dust. The electric dust collector may be a dry electric dust collector or a wet electric dust collector. When the exhaust gas contains water vapor gas, the dust in the exhaust gas is easily captured, and the performance of the electric dust collector can be improved. This is because when water vapor is contained in the exhaust gas, the resistivity of the dust decreases, making it easier for the dust to be charged, and the dust removal rate is improved. Therefore, from the viewpoint of increasing the dust removal rate, the electric dust collector may be a wet electric dust collector.

[0025] An example of an apparatus for producing cement clinker is described below. The apparatus may be used to carry out a method for operating a clinker cooler and a method for producing cement clinker.

[0026] The cement clinker manufacturing apparatus 10 of FIG. 1 includes a preheater 12, a kiln 14, and a clinker cooler 16. The preheater 12 preheats the cement raw materials. The preheater 12 is, for example, a new suspension preheater (NSP) having a plurality of cyclones constituting a multi-stage cyclone and a calciner 18. The preheater 12 may have four or five cyclones. Exhaust gas from the kiln 14 is introduced into the preheater 12. The preheater 12 brings high-temperature gas, including the exhaust gas from the kiln 14, into contact with the cement raw materials, and separates the gas from the cement raw materials in the cyclones. Exhaust gas used for heat exchange is discharged from the top cyclone of the preheater 12. The cement raw materials preheated by the preheater 12 including the calciner 18 are introduced into the kiln 14.

[0027] The kiln 14 burns the cement raw materials to produce a burned product. The kiln 14 burns the cement raw materials preheated by the preheater 12. The kiln 14 is, for example, a rotary kiln. The kiln 14 may have a drum body and a burner that introduces combustion gas into the drum body. The drum body of the kiln 14 (rotary kiln) is configured to rotate around an axis along its longitudinal direction. The rotation axis of the drum body is slightly inclined with respect to the horizontal, and the upstream side is higher than the downstream side. Therefore, the burned product moves from one end side to the other end side of the kiln 14 while being stirred by the rotation of the kiln 14. The burned product produced in the kiln 14 is introduced into the clinker cooler 16. The temperature of the burned product introduced from the kiln 14 to the clinker cooler 16 may be, for example, 800 to 1000°C.

[0028] The clinker cooler 16 cools the burnt material discharged from the kiln 14. The clinker cooler 16 cools the burnt material using cooling air (gas). The clinker cooler 16 is also called an air quenching cooler. The clinker cooler 16 is configured to transport the burnt material through multiple grates while blowing in cooling air from the bottom of the grates.

[0029] In the clinker cooler 16, the burnt material is cooled (quenched) by heat exchange between the cooling air and the burnt material. A part of the exhaust gas (air) that has become hot by heat exchange with the burnt material may be introduced into the kiln 14 and / or the calciner 18 as secondary air for combustion.

[0030] 2 shows a schematic diagram of the operating state of the clinker cooler 16. The clinker cooler 16 includes a casing 16a, a conveying section 20, an outlet section 29, and an air delivery section 30. The casing 16a and the conveying section 20 form an internal space 40 in which the clinker is cooled while being conveyed. One end of the internal space 40 extending horizontally communicates with the kiln 14. The burnt material 80 produced in the kiln 14 is introduced into the clinker cooler 16.

[0031] The conveying unit 20 conveys the burned material 80 introduced from the kiln 14 from left to right in Fig. 2. The direction in which the clinker is conveyed by the conveying unit 20 corresponds to the direction in which the internal space 40 formed by the casing 16a extends.

[0032] As shown in FIG. 3, the conveying section 20 is configured with movable grates 21 and fixed grates 22 arranged alternately. The movable grate 21 has a grate plate 24 and a support 26A that supports the grate plate 24. The fixed grate 22 has a grate plate 24 and a support 26B that supports the grate plate 24. In FIG. 3, two sets of movable grates 21 and fixed grates 22 are shown in a side view, but the number of sets is not particularly limited. The baked material 80 is conveyed on the grate plate 24 from upstream to downstream, that is, from left to right in FIG. 3. The grate plate 24 may be made of metal, for example.

[0033] The movable grate 21 and the fixed grate 22 are arranged alternately to form a portion that supports the baked material 80 in the internal space 40 formed in the casing 16a. The grate plates 24 of the movable grate 21 and the fixed grate 22 are arranged in a row so that the upper surface (main surface) that supports the baked material 80 is inclined. Specifically, each grate plate 24 is inclined so that the upper surface faces upward as it advances in the conveying direction of the baked material 80. The inclination angle of the upper surface of each grate plate 24 from the horizontal direction is, for example, about 10°. When focusing on a pair of grate plates 24 adjacent to each other in the conveying direction of the baked material 80, the tip end of the grate plate 24 located upstream overlaps the rear end of the grate plate 24 located downstream from above.

[0034] The movable grate 21 is configured to be capable of reciprocating in a fixed direction at a predetermined pitch. For example, it is reciprocated in the direction of the arrow shown in FIG. 3 by a drive unit (not shown). This reciprocating motion pushes the material to be baked 80 on the grate plate 24 downstream. The fixed grate 22 is not driven by a drive unit and its position is fixed. When the movable grate 21 reciprocates, the material to be baked 80 gradually moves along the direction in which the movable grate 21 and the fixed grate 22 are aligned.

[0035] 4(A) and 4(B) are schematic top views of the upper surface of the grate plate 24 as viewed from a direction perpendicular to the upper surface. Each of the grate plates 24 has a slit 55 (opening) or one or more holes 56 (openings). An air delivery section 30 is provided below the grate plate 24. The air delivery section 30 delivers cooling air (hereinafter referred to as "cooling air") from below the grate plate 24 toward the grate plate 24. The cooling air is air for cooling the baked product, and may be air at room temperature, for example. The air delivered from the air delivery section 30 passes through the slit 55 or hole 56 and is introduced into the internal space 40 in which the baked product 80 exists. Either one of the grate plates 24 shown in FIG. 4(A) or FIG. 4(B) may be used, or both grate plates 24 may be used in combination.

[0036] Returning to FIG. 2, the conveying section 20 may be divided into two or more sections along the conveying direction of the baked material 80. The two or more sections in the conveying section 20 may be arranged in order from the upstream in the conveying direction of the baked material 80. The conveying section 20 may be divided into two or more sections depending on the difference in the driving source for driving the movable grate 21. The air delivery section 30 may be provided independently for each section. In the example of FIG. 2, the conveying section 20 is divided into two sections along the conveying direction of the baked material 80, and the air delivery section 30A is provided in the upstream section, and the air delivery section 30B is provided in the downstream section. The air volumes of the cooling air from the air delivery sections 30A and 30B may be independently adjustable. The grate plate 24 of FIG. 4(A) may be provided in the upstream section, and the grate plate 24 of FIG. 4(B) may be provided in the downstream section.

[0037] The calcined material 80 introduced from the kiln 14 is introduced into the internal space 40 above the upstream section of the conveying section 20 and conveyed from left to right in FIG. 2. The calcined material 80 is heated by the combustion of the burner 17. Cooling air from the air delivery section 30A is blown onto the calcined material 80, gradually cooling it. The blown cooling air exchanges heat with the calcined material 80 and becomes high-temperature exhaust gas (air). The high-temperature exhaust gas entrains fine components contained in the calcined material 80 as dust.

[0038] Since the temperature of the calcined material 80 is higher in the internal space 40A above the upstream section of the conveying section 20 than in the internal space 40B above the downstream section, the exhaust gas (air) obtained by contact between the calcined material 80 and the cooling air is at a high temperature. Such high-temperature exhaust gas flows through the flow path 23 and is introduced into the calciner 18, where it is used as secondary air for combustion. This allows the exhaust heat to be effectively utilized.

[0039] The burnt material 80, which has been cooled to a certain degree in the internal space 40A on the upstream side of the clinker cooler 16, is transported to the internal space 40B on the downstream side. In the internal space 40B, cooling air is blown onto the burnt material 80 from the air delivery section 30B via the grate plate 24, and the burnt material 80 is further cooled. The blown cooling air exchanges heat with the burnt material 80 and becomes exhaust gas (air). The exhaust gas entrains fine components contained in the burnt material 80 as dust.

[0040] A spray nozzle 25 for spraying water droplets 42 into the internal space 40B is attached to the upper wall of the clinker cooler 16, which is constituted by the casing 16a. The spray nozzle 25 is attached downstream of the flow path 23. The spray nozzle 25 sprays the water droplets 42 toward the downstream of the clinker cooler 16. This allows the temperature of the flue gas discharged from the flow path 23 to be kept sufficiently high even if the water droplets 42 are sprayed from the spray nozzle 25 into the internal space 40. The spray nozzle 25 may be, for example, a two-layer nozzle that mixes air and water and sprays the water droplets 42. The water droplets 42 sprayed from the spray nozzle 25 are mixed with the flue gas in the internal space 40B and vaporized. The flue gas is cooled by the water droplets 42 sprayed from the spray nozzle 25 and the air. The flue gas containing air, dust, and water vapor flows from the left to right in the internal space 40B and is discharged from the flow path 27 connected to the downstream side of the clinker cooler 16.

[0041] The water droplets 42 sprayed from the spray nozzle 25 are sprayed so that they are all vaporized before reaching the rear end region of the conveying section 20 that conveys the burned material 80. Here, the rear end region of the conveying section 20 is an imaginary plane VP drawn vertically upward from the rear end of the conveying section 20, as shown in Fig. 2. This makes it possible to prevent dust containing liquid water from coming into contact with the inner wall on the downstream side of the clinker cooler 16 and the curtain chain 28 described later, resulting in the formation of a coating.

[0042] Here, the time required for the water droplets 42 sprayed into the internal space 40 of the clinker cooler 16 to evaporate (evaporation time) can be estimated by the following empirical formulas (1) and (2).

number

[0043] The meanings of the symbols in the above formulas (1), (2) and (3) are as follows: t: Evaporation time of water droplet 42 [sec] D: Droplet diameter of water droplet 42 [mm] θ1: Exhaust gas temperature before being cooled by water droplets 42 [℃] θ2: Exhaust gas temperature cooled by water droplets 42 [℃] θ b : Pressure 1kg / cm 2 Boiling point of a water droplet at 42 G [℃] Q0: Heat of vaporization of water at boiling point 100℃ [kcal / kg] λ: Thermal conductivity of the gas before the water droplets 42 are sprayed [kcal / m·h·℃] λm: Thermal conductivity of the mixture of exhaust gas and water vapor gas [kcal / m h °C] θ g : Average gas temperature at the inlet and outlet Cps: Low pressure specific heat of water vapor gas [kcal / kg°C] A, B, C: Constants determined by experiment

[0044] If the distance from the spray nozzle 25 to the rear end region (virtual plane VP) of the transfer section 20 is L1, the time it takes for the water droplets 42 sprayed from the spray nozzle 25 to reach the rear end region of the transfer section 20 can be calculated as L1 / S, where S is the gas flow rate in the internal space 40B [m / s]. If the droplet diameter of the water droplets 42 and the amount of the water droplets 42 are adjusted so that t (evaporation time) calculated by the above formulas (1) and (2) satisfies t≦L1 / S, the water droplets 42 can be completely vaporized before reaching the rear end region of the transfer section 20. The distance L1 may be, for example, 2 to 6 m.

[0045] From the viewpoint of sufficiently suppressing coating in the clinker cooler 16, the droplet diameter D of the water droplets 42 may be 160 μm or less, may be less than 100 μm, or may be 90 μm or less. 3At a flow rate of 1,000 to 5,000 kg / h, the amount of water droplets 42 sprayed may be 1,000 to 5,000 kg / h. This makes it possible to sufficiently reduce the temperature of the exhaust gas flowing through the internal space 40B while sufficiently suppressing the occurrence of coating. As a result, the performance of the electric dust collector 60 provided downstream of the clinker cooler 16 can be sufficiently maintained. The temperature θ1 is the temperature of the exhaust gas in a portion of the internal space 40B immediately before the water droplets 42 are sprayed from the spray nozzle 25, and may be, for example, 500 to 800°C, or 600 to 700°C.

[0046] The calcined material 80 cooled in the clinker cooler 16 is discharged to the outside of the clinker cooler 16 from the discharge section 29 provided downstream of the clinker cooler 16. The discharge section 29 may be provided with, for example, a hammer crusher. The calcined material 80 is crushed by the hammer crusher to obtain a cement clinker 82. The cement clinker 82 may be finely pulverized as necessary. The cement clinker 82 may be mixed with gypsum using a mill or the like to obtain a cement composition such as Portland cement. It is not essential to provide the discharge section 29 with a hammer crusher, and the calcined material 80 discharged from the discharge section 29 may be crushed together with gypsum in a mill to obtain a cement composition such as Portland cement.

[0047] A metallic curtain chain 28 is attached to the casing 16a of the clinker cooler 16. The curtain chain 28 has a function of suppressing damage to the refractory constituting the inner wall of the casing 16a caused by fragments of the burnt material 80 generated when the burnt material 80 is crushed by the hammer crusher. For this reason, the curtain chain 28 is attached to a portion of the clinker cooler 16 near the outlet section 29. The curtain chain 28 may be one piece or multiple pieces. In order not to impede the transport of the burnt material 80 by the transport section 20, the curtain chain 28 is attached to the ceiling wall of the clinker cooler 16 formed by the casing 16a.

[0048] The curtain chain 28 may be attached upstream of the rear end region (virtual plane VP) of the transport unit 20. From the viewpoint of suppressing coating on the curtain chain 28, it is preferable that all the water droplets 42 sprayed from the spray nozzle 25 are vaporized before reaching the curtain chain 28. Assuming the distance from the spray nozzle 25 to the curtain chain 28 is L2, the time it takes for the water droplets 42 sprayed from the spray nozzle 25 to reach the curtain chain 28 can be calculated as L2 / S, where S [m / s] is the gas flow velocity in the internal space 40B. By adjusting the droplet diameter and the amount of the water droplets 42 so that the evaporation time t obtained from the above formulas (1) and (2) satisfies t≦L2 / S, all the water droplets 42 can be vaporized before reaching the curtain chain 28. The distance L2 satisfies L2<L1 and may be, for example, 1 to 5 m.

[0049] The exhaust gas in the internal space 40B of the clinker cooler 16 contains air, dust, and water vapor gas. This exhaust gas is led out of the clinker cooler 16 through a flow path 27 connected to the downstream side of the clinker cooler 16 and introduced into the electrostatic precipitator 60 shown in FIG. 1. In the electrostatic precipitator 60, the dust contained in the exhaust gas is captured, and the exhaust gas with a sufficiently reduced dust concentration compared to the exhaust gas is exhausted. A temperature measurement unit (T) for measuring the temperature of the exhaust gas when it is introduced into the electrostatic precipitator 60 is provided in the flow path 27. The temperature measurement unit (T) may be, for example, a thermocouple.

[0050] Since the water droplets 42 are sprayed from the spray nozzle 25 in the internal space 40B, the temperature of the exhaust gas introduced into the electrostatic precipitator 60 can be lowered. The temperature measured by the temperature measurement unit (T) is preferably maintained at 400 °C or lower, more preferably maintained at 390 °C or lower, and even more preferably maintained at 380 °C or lower. Thereby, the dust capture ability of the electrostatic precipitator 60 can be made sufficiently high. The lower limit of the temperature measured by the temperature measurement unit (T) may be, for example, 200 °C or may be 250 °C.

[0051] The temperature measuring unit (T) outputs information about the measured value to the control unit 50. The control unit 50 may be a computer that controls at least some of the various devices included in the cement clinker manufacturing apparatus 10. The control unit 50 may be configured to be able to control the amount of water droplets 42 sprayed from the spray nozzle 25 and the amount of cooling air sent out from the air sending unit 30. The control unit 50 includes hardware such as a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and an input / output interface. The control unit 50 may include a driver (driver circuit). The driver of the control unit 50 may output drive power to a drive motor included in each drive unit such as an actuator 52 that adjusts the amount of water supplied to the spray nozzle 25 and the air sending unit 30.

[0052] 5 shows a process flow showing a series of processes executed by the control unit 50. The control unit 50 acquires information about the temperature T1 measured by the temperature measurement unit (T) (step S1). The control unit 50 compares the information with information pre-stored in a storage unit such as a ROM, and determines whether the temperature T1 is below the upper limit value Tmax (step S2). If it is determined that the temperature T1 is below the upper limit value Tmax, the control unit 50 then compares the information about the temperature T1 with information pre-stored in a storage unit such as a ROM, and determines whether the temperature T1 exceeds the lower limit value Tmin (step S3). If it is determined that the temperature T1 exceeds the lower limit value Tmin, the process flow of FIG. 5 ends.

[0053] On the other hand, when it is determined in step S2 that the temperature T1 is equal to or higher than the upper limit value Tmax, the control unit 50 outputs a control signal to increase the amount of water droplets 42 sprayed from the spray nozzle 25. For example, when the control signal is output to the actuator 52 that adjusts the amount of water supplied to the spray nozzle 25, the amount of water droplets 42 sprayed is increased (step S4).

[0054] After a predetermined time has elapsed, steps S1 and S2 are performed again. If it is determined in step S2 that the temperature T1 is less than the upper limit value Tmax, then step S3 is performed. If it is determined in step S3 that the temperature T1 is less than the lower limit value Tmin, the control unit 50 outputs a control signal for reducing the amount of water droplets 42 sprayed from the spray nozzle 25. For example, when the control signal is output to the actuator 52 that adjusts the amount of water sprayed supplied to the spray nozzle 25, the amount of water droplets 42 sprayed is reduced (step S5).

[0055] After a predetermined time has elapsed since step S5 was performed, steps S1 and S2 are performed again. If it is determined in step S2 that the temperature T1 is less than the upper limit value Tmax, step S3 is subsequently performed. If it is determined that the temperature T1 is greater than the lower limit value Tmin, the process flow of FIG. 5 ends. The upper limit value Tmax may be 400°C, 390°C, or 380°C. The lower limit value Tmin may be 200°C or 250°C. By reducing the fluctuation of the temperature T1, the electrostatic precipitator 60 can be operated stably.

[0056] In this series of processes, the control unit 50 first executes step S1. The timing for acquiring the temperature T1 in step S1 may be determined in advance. By repeatedly performing the series of processes at a predetermined cycle, the cement clinker 82 can be stably produced while maintaining the temperature T1 within a predetermined range.

[0057] In this processing flow, the temperature T1 is adjusted by the amount of water droplets 42 sprayed, but the temperature T1 may be adjusted by another means. For example, the temperature T1 may be adjusted by the amount of cooling air sent out from the air delivery section 30B, or the temperature T1 may be adjusted by both the amount of cooling air and the amount of water sprayed. For example, the initial adjustment of temperature T1 is performed by the amount of water droplets 42 sprayed, and if the amount is increased beyond this amount, there is a possibility that the water droplets 42 will not all be vaporized before reaching the rear end region of the transport section, in which case the temperature T1 may be adjusted by the amount of cooling air.

[0058] A dust concentration measuring section (D) for measuring the dust concentration in the exhaust gas from the electric dust collector 60 may be provided. A commercially available dust meter can be used as the dust concentration measuring section (D). The dust concentration in the exhaust gas measured by the dust concentration measuring section (D) is preferably 40 mg / Nm3 or less. 3 should be kept below 35 mg / Nm 3 and more preferably 30 mg / Nm 3 The following is maintained:

[0059] The cement clinker manufacturing apparatus 10 includes a spray nozzle 25 for spraying water droplets 42 into the inside of the clinker cooler 16. The spray nozzle 25 sprays the water droplets 42 so that all of the water droplets 42 are vaporized before reaching the end of the conveying section 20 that conveys the clinker cooler 16. This reduces the frequency with which wet dust impinges on refractories and the like downstream of the clinker cooler 16, and can suppress coating on the inner wall of the clinker cooler 16 and the curtain chain 28. As a result, the frequency with which the clinker cooler 16 is opened and cleaned can be reduced, and maintenance costs can be reduced. In addition, the cement clinker 82 can be stably manufactured. Furthermore, the temperature of the cement clinker 82 can be reduced by spraying the water droplets 42. The cement clinker 82 is mixed with gypsum to form a cement composition. If the temperature of the cement clinker 82 can be reduced, dehydration of the gypsum caused by mixing with the high-temperature cement clinker 82 can be suppressed, and the quality of the cement composition can be stabilized.

[0060] The cement clinker manufacturing apparatus 10 or its modified example can be used to perform a method for manufacturing cement clinker and a method for operating a clinker cooler. Both of these methods include a step of spraying water droplets 42 inside the clinker cooler 16, and the water droplets 42 are sprayed so that they are all vaporized before reaching the rear end region (virtual plane VP) of the conveying section 20 that conveys the burned material 80 in the clinker cooler 16. Therefore, coating on the inner wall of the clinker cooler 16 and the curtain chain 28 can be suppressed. As a result, the frequency of opening and cleaning the clinker cooler 16 can be reduced, and maintenance costs can be reduced. In addition, the production of cement clinker 82 can be continued stably. Furthermore, the temperature of the cement clinker 82 can be reduced by spraying the water droplets 42. The cement clinker 82 is mixed with gypsum to form a cement composition. If the temperature of the cement clinker 82 can be reduced, dehydration of the gypsum caused by mixing with the high-temperature cement clinker 82 can be suppressed, and the quality of the cement composition can be stabilized.

[0061] Although the embodiment of the present disclosure has been described above, the present disclosure is not limited to the above embodiment. For example, the conveying section 20 of the clinker cooler 16 is divided into two sections, an upstream side and a downstream side, but may be divided into three or more sections, or may not be divided at all. The exhaust gas of the clinker cooler 16 is used as secondary air for combustion in the calciner 18, but is not limited thereto. For example, it may be used as secondary air for combustion in a boiler, or may be used as a heat source for a sewage treatment facility. EXAMPLES

[0062] The present disclosure will be described in more detail with reference to examples and comparative examples, but the present disclosure is not limited to the following examples.

[0063] Comparative Example 1 Cement clinker was produced using a cement clinker production device equipped with a rotary kiln for burning cement raw materials, a clinker cooler for cooling the burned material obtained in the rotary kiln, and an electric dust collector for collecting dust in the exhaust gas of the clinker cooler. The device had a structure similar to that of the clinker cooler 16 shown in FIG. 2. Cement clinker was produced continuously for about four months, during which the exhaust gas temperature at the inlet of the electric dust collector and the dust concentration in the exhaust gas discharged from the electric dust collector were measured. During this time, water droplets were not sprayed from the spray nozzle 25. The results were as shown to the left of the dashed line in FIG. 6.

[0064] Example 1 Using the same cement clinker manufacturing apparatus as in Comparative Example 1, cement clinker was continuously manufactured for about two months, and during that time, the exhaust gas temperature at the inlet of the electrostatic precipitator and the dust concentration in the exhaust gas from the electrostatic precipitator were measured. During this time, 3,000 kg / h of water droplets 42 were continuously supplied from the spray nozzle 25 (a commercially available two-fluid nozzle) together with air. The droplet diameter D of the water droplets 42 based on the specifications of the spray nozzle 25 was 90 μm. The flow rate of the exhaust gas flowing into the internal space 40B was 105,000 Nm 3 / h. The temperature of the exhaust gas (temperature θ1) in a portion of the internal space 40B immediately before the water droplets 42 were sprayed from the spray nozzle 25 was 650° C. The operating conditions other than the water droplets 42 were the same as in Comparative Example 1. The results are shown to the right of the dashed line in FIG. 6.

[0065] 6, the variation in exhaust gas temperature was smaller in Example 1 in which water droplets 42 were sprayed from the spray nozzle 25. The average and maximum values ​​of the exhaust gas temperature are shown in Table 1.

[0066] [Table 1]

[0067] As shown in Table 1, both the exhaust gas temperature and dust concentration were lower in Example 1 than in Comparative Example 1. The reason for the decrease in the maximum dust concentration is that the exhaust gas temperature decreased and water vapor gas was contained in the exhaust gas, which stabilized the operation of the electrostatic precipitator and enabled the dust collection capacity to be continuously maintained at a high level.

[0068] Fig. 7(A) is a photograph of the inside of the clinker cooler before the start of operation in Example 1, and Fig. 7(B) is a photograph of the same location after two months of operation. Comparing the two photographs, it can be seen that almost no coating was formed inside the clinker cooler.

[0069] Comparative Example 2 The spray nozzle 25 of Example 1 was replaced with another one, and cement clinker was produced under the same conditions as in Example 1. The specifications of the spray nozzle 25 used in Example 1 and the spray nozzle used in Comparative Example 2 are shown in Table 2.

[0070] [Table 2]

[0071] As shown in Table 2, the droplet size (diameter) in Comparative Example 2 was 630 μm, which was considerably larger than that in Example 1. FIGS. 8(A) and (B) are photographs of the inside of a clinker cooler in the cement clinker manufacturing apparatus of Comparative Example 2 after two months of operation. FIGS. 8(A) and (B) are photographs taken at different locations during the same period. As shown in these photographs, a large amount of coating occurred in the clinker cooler in Comparative Example 2. The reason why such a large amount of coating occurred, despite the fact that the amount of water was less than that in Example 1, was that the droplet size was large and the water droplets did not vaporize sufficiently in the clinker cooler. [Explanation of symbols]

[0072] 10... manufacturing equipment, 12... preheater, 14... kiln, 16... clinker cooler, 16a... casing, 17... burner, 18... calciner, 20... conveying section, 21... movable grate, 22... fixed grate, 23, 27... flow path, 24... grate plate, 25... spray nozzle, 26A, 26B... support, 28... curtain chain, 29... outlet section, 30, 30A, 30B... air delivery section, 40, 40A, 40B... internal space, 42... water droplets, 50... control section, 52... actuator, 55... slit, 56... hole, 60... electric dust collector, 80... calcined product, 82... cement clinker, VP... virtual surface.

Claims

1. A method for operating a clinker cooler that cools a burned cement raw material while transporting the material, comprising the steps of: spraying water droplets into the interior of the clinker cooler; The method for operating a clinker cooler, wherein the water droplets are all vaporized by the time they reach a rear end region of a conveying section that conveys the burnt material in the clinker cooler.

2. 2. The method for operating a clinker cooler according to claim 1, further comprising a step of introducing exhaust gas from the clinker cooler, which contains at least a portion of the water vapor gas produced by vaporization of the water droplets, into an electric dust collector to recover dust.

3. 3. The method for operating a clinker cooler according to claim 2, wherein the temperature of the flue gas when introduced into the electrostatic precipitator is maintained at 400° C. or lower.

4. The method for operating a clinker cooler according to claim 2 or 3, further comprising a step of adjusting the amount of water droplets sprayed based on a measured value of the temperature of the flue gas when it is introduced into the electric dust collector.

5. The clinker cooler is provided with a curtain chain downstream of a spray nozzle that sprays the water droplets, The method for operating a clinker cooler according to any one of claims 1 to 3, wherein the water droplets are all vaporized by the time they reach the curtain chain.

6. The method for operating a clinker cooler according to any one of claims 1 to 3, wherein the spray nozzle for spraying the water droplets sprays the water droplets having a droplet diameter of 160 μm or less.

7. A method for producing cement clinker, comprising: a step of burning a cement raw material in a kiln to obtain a burned product; and a step of cooling the burned product in a clinker cooler to obtain cement clinker, A method for producing cement clinker, comprising operating the clinker cooler according to any one of claims 1 to 3.

8. A cement clinker manufacturing apparatus comprising: a kiln for burning cement raw materials to obtain a burned product; and a clinker cooler for cooling the burned product while transporting it to obtain cement clinker, The clinker cooler is provided with a spray nozzle for spraying water droplets therein, The cement clinker manufacturing apparatus, wherein the water droplets are all vaporized by the time they reach a rear end region of a conveying section that conveys the clinker cooler.

9. An electric dust collector is provided for collecting dust from the exhaust gas of the clinker cooler.

9. The cement clinker manufacturing apparatus according to claim 8, wherein the exhaust gas introduced into the electric dust collector contains at least a part of the water vapor gas generated by vaporization of the water droplets.

10. The cement clinker manufacturing apparatus according to claim 9 , which is configured to maintain the temperature of the flue gas at 400° C. or lower when the flue gas is introduced into the electric dust collector.

11. a temperature measuring unit that measures the temperature of the exhaust gas when it is introduced into the electric dust collector; 11. The cement clinker manufacturing apparatus according to claim 9 or 10, further comprising: a control unit that adjusts the amount of the water droplets sprayed from the spray nozzle based on the measured value measured by the temperature measuring unit.

12. the clinker cooler includes a curtain chain downstream of the spray nozzle; The cement clinker manufacturing apparatus according to any one of claims 8 to 10, wherein the water droplets are all vaporized before reaching the curtain chain.

13. The cement clinker manufacturing apparatus according to any one of claims 8 to 10, wherein the spray nozzle is configured to spray the water droplets having a droplet diameter of 160 μm or less.

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