Method for producing cement clinker and cement firing facility

Abstract

To provide a method for producing cement clinker and a cement firing facility, in which the amount of carbon dioxide contained in combustion exhaust gas generated by the cement firing facility is adjusted without having to perform large-scale modification of the cement firing facility.SOLUTION: Provided is a method for producing cement clinker using a cement firing facility comprising a drying and grinding device for cement raw material, a suspension preheater, a rotary kiln, and a clinker cooler, wherein predetermined adjustment means included in a specific cyclone dust collector constituting the suspension preheater is used to adjust the dust collection efficiency of the cyclone dust collector. Also provided is a cement firing facility.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present disclosure relates to a method for producing cement clinker and a cement calcination facility. [Background technology]

[0002] In recent years, interest in global warming has increased, and there is a demand for reducing the amount of carbon dioxide emitted into the atmosphere. In order to reduce the amount of carbon dioxide-containing exhaust gases emitted into the atmosphere during operation at various facilities such as power plants, incinerators, cement plants, steelworks, and factory facilities, separation and capture of carbon dioxide in the exhaust gas is being considered. In particular, reducing the amount of carbon dioxide emitted from cement plants is considered to be an important issue.

[0003] An example of the configuration of a typical cement plant is that disclosed in Patent Document 1, which is a cement manufacturing facility including a preheater that preheats cement raw materials by heat exchange with high-temperature gas, a cement calcination furnace that calcines the cement raw materials to produce cement clinker, a cooling device that directs a portion of the air that has been heated by heat exchange with the cement clinker as burner combustion air for the cement calcination furnace, an absorption tower that stores an absorbing liquid that absorbs carbon dioxide, and a regeneration tower that volatilizes carbon dioxide by heating the absorbing liquid, and an exhaust gas introduction pipe that uses exhaust gas from the preheater as a heating source via the regeneration tower and then directs it to the absorption tower.

[0004] As an example of the above-mentioned suspension preheater, a heating device is known, as shown in Patent Document 2, which has a structure in which multiple independent hot gases are flowed into each of multiple air ducts formed by multiple dust collectors, while a powdered material is fed from the air duct leading to the uppermost dust collector of the multiple dust collectors, passed through the dust collectors in sequence, and discharged from the bottom of the lowest dust collector.

[0005] Patent Document 3 also describes a cyclone-type preheating device for preheating cement clinker raw materials, a rotary kiln for burning the preheated cement clinker raw materials to obtain cement clinker, a calciner disposed upstream of the rotary kiln for promoting decarbonation of the cement clinker raw materials, a preheated raw material supply passage for supplying the cement clinker raw materials from the preheating device to the calciner, a clinker cooler for cooling the cement clinker, and a clinker cooler for cooling the cement clinker. The present invention discloses a cement clinker production system including a kiln exhaust gas exhaust passage for discharging carbon dioxide-containing exhaust gas generated in the calciner after passing through an oxygen-enriched combustion supporting gas supply device and a calciner for supplying the combustion supporting gas to the calciner, a first recovery means for recovering a slaked lime-containing raw material from the carbon dioxide-containing exhaust gas, and a calciner exhaust gas supply passage for merging a part of the carbon dioxide-containing exhaust gas with the combustion supporting gas downstream of the first recovery means of the calciner exhaust gas supply passage. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 59-110485 [Patent Document 2] Japanese Patent Publication No. 55-22322 [Patent Document 3] Patent Publication No. 2022-148255 Summary of the Invention [Problem to be solved by the invention]

[0007] The cement calcination facility disclosed in Patent Document 1 is a facility that uses the exhaust gas discharged from a preheater, which preheats cement raw materials by heat exchange with high-temperature gas, as a heat source via a regeneration tower and then leads it to an absorption tower, thereby utilizing the thermal energy of the exhaust gas generated in the cement manufacturing facility to inexpensively remove carbon dioxide from the exhaust gas. However, because the concentration of carbon dioxide contained in the exhaust gas is low, the equipment for recovering carbon dioxide, i.e., the absorption tower and regeneration tower, must be large, and there is room for improvement in this regard.

[0008] The cement clinker production system disclosed in Patent Document 3 can be an effective system for new construction. However, for example, application to an existing cement calcination facility would require large-scale modifications to the facility, such as modifications to the exhaust pipes for discharging the kiln exhaust gas and the calciner exhaust gas, and the raw material supply pipes, as well as modifications to the calciner and other equipment.

[0009] The present invention has been made in consideration of the above circumstances, and has an object to provide a cement clinker manufacturing method and cement burning equipment that adjusts the amount of carbon dioxide contained in the combustion exhaust gas generated in the cement burning equipment without large-scale modification of the cement burning equipment. [Means for solving the problem]

[0010] In order to solve the above problems, the present invention provides the following method for producing cement clinker. 1. Drying and crushing equipment for drying and crushing cement raw materials into powder raw materials; a suspension preheater for preheating and calcining the powdered raw material; a rotary kiln for burning the preheated and calcined powdered raw material into cement clinker; and A method for producing cement clinker using a cement calcination facility including a cement clinker cooler for cooling the cement clinker, The suspension preheater is A calciner for calcining the powdered raw material, a C-type air duct having three or more stages of cyclone dust collectors for collecting the powder raw material and a gas flow path connecting the three or more stages of cyclone dust collectors in sequence, through which the calciner combustion exhaust gas discharged from the calciner passes; A cyclone dust collector having three or more stages for collecting the powder raw material and a gas flow path for sequentially connecting the three or more stages of cyclone dust collectors, and a K-type air duct through which the kiln combustion exhaust gas discharged from the rotary kiln passes; a raw material conduit KI connecting the cyclone dust collector of the K system air duct and a gas flow path for supplying the calciner combustion exhaust gas to the cyclone dust collector of the C system air duct at the same stage as the cyclone dust collector of the K system air duct; A raw material conduit CI that connects the cyclone dust collector of the C system air duct and a gas flow path that supplies the kiln combustion exhaust gas to the cyclone dust collector of the K system air duct, which is one stage below the cyclone dust collector of the C system air duct; A raw material conduit K-II that connects the lowest cyclone dust collector in the K system air duct and the calciner; A raw material conduit C-II connecting the lowest cyclone dust collector of the C system air duct and the rotary kiln; a powder raw material supplying device that supplies the powder raw material to a topmost cyclone dust collector of at least one of the two air passages; At least one of the cyclone dust collectors at the lowest stage in the two air ducts and at least one of the cyclone dust collectors one stage above the lowest stage have a means for adjusting the dust collection efficiency of the powder raw material, The dust collection efficiency of the cyclone dust collector is adjusted by the adjustment means. A method for producing cement clinker.

[0011] The present invention provides the following method for producing cement clinker as a preferred embodiment. 2. The method for producing cement clinker as described in the above 1, wherein the dust collection efficiency of the lowermost cyclone dust collector is reduced by the adjustment means. 3. A method for producing cement clinker as described in 1 or 2 above, wherein the dust collection efficiency of the cyclone dust collector one stage above the lowest stage is increased by the adjustment means. 4. The method for producing cement clinker according to any one of 1 to 3 above, wherein the temperature of the kiln combustion exhaust gas after passing through the cyclone dust collector one level above the lowest level in the K system air duct is 700°C or lower. 5. The method for producing cement clinker according to any one of the above 1 to 4, wherein carbon dioxide is recovered from the calciner combustion exhaust gas using a carbon dioxide recovery facility. 6. The method for producing cement clinker according to any one of 1 to 5 above, wherein at least the kiln combustion exhaust gas is used for drying the cement raw materials. 7. The drying and grinding device has a drying device or a drying and grinding device, 7. The method for producing cement clinker according to any one of 1 to 6 above, wherein at least the kiln combustion exhaust gas is supplied to the drying equipment or the drying and crushing equipment.

[0012] The present invention also provides the following cement burning equipment. 8. Drying and crushing equipment for drying and crushing cement raw materials into powder raw materials; a suspension preheater for preheating and calcining the powdered raw material; a rotary kiln for burning the preheated and calcined powdered raw material into cement clinker; and A cement burning facility including a cement clinker cooler for cooling the cement clinker, The suspension preheater is A calciner for calcining the powdered raw material, a C-type air duct having three or more stages of cyclone dust collectors for collecting the powder raw material and a gas flow path connecting the three or more stages of cyclone dust collectors in sequence, through which the calciner combustion exhaust gas discharged from the calciner passes; A cyclone dust collector having three or more stages for collecting the powder raw material and a gas flow path for sequentially connecting the three or more stages of cyclone dust collectors, and a K-type air duct through which the kiln combustion exhaust gas discharged from the rotary kiln passes; a raw material conduit KI connecting the cyclone dust collector of the K system air duct and a gas flow path for supplying the calciner combustion exhaust gas to the cyclone dust collector of the C system air duct at the same stage as the cyclone dust collector of the K system air duct; A raw material conduit CI that connects the cyclone dust collector of the C system air duct and a gas flow path that supplies the kiln combustion exhaust gas to the cyclone dust collector of the K system air duct, which is one stage below the cyclone dust collector of the C system air duct; A raw material conduit K-II that connects the lowest cyclone dust collector in the K system air duct and the calciner; A raw material conduit C-II connecting the lowest cyclone dust collector of the C system air duct and the rotary kiln; a powder raw material supplying device that supplies the powder raw material to a topmost cyclone dust collector of at least one of the two air passages; At least one of the cyclone dust collectors at the lowest stage in the two air passages and at least one of the cyclone dust collectors one stage above the lowest stage have a means for adjusting the dust collection efficiency of the powder raw material. Cement baking equipment. 9. The cement calcination facility according to claim 8, further comprising a carbon dioxide recovery facility for recovering carbon dioxide from the calciner combustion exhaust gas. 10. The drying and grinding device comprises a drying device or a drying and grinding device; 10. The cement firing facility according to claim 8 or 9, further comprising an exhaust gas supply pipe for supplying at least the kiln combustion exhaust gas to the drying equipment or the drying and crushing equipment. Effect of the Invention

[0013] According to the present invention, it is possible to provide a cement clinker manufacturing method and cement calcination facility that adjust the amount of carbon dioxide contained in the combustion exhaust gas generated in the cement calcination facility without large-scale modification of the cement calcination facility. [Brief description of the drawings]

[0014] [Figure 1]FIG. 2 is a schematic diagram showing a preferred embodiment of cement burning equipment used in the manufacturing method of the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, an embodiment of the present invention (hereinafter, sometimes referred to as "the present embodiment") will be described. The present invention is not limited to the following embodiment, and can be implemented with any modification within the scope that does not impair the effects of the invention. In this specification, the expression "AA to BB" for a numerical range means "AA or more and BB or less". In this specification, the numerical values ​​related to "above", "below" and "to" in the description of a numerical range are numerical values ​​that can be arbitrarily combined. For example, when a certain numerical range is described as "CC to DD" and "EE to FF", the numerical ranges "CC to FF" and "EE to DD" are also included.

[0016] [Manufacturing method of cement clinker] The method for producing cement clinker according to the present embodiment includes the steps of: A drying and crushing device for drying and crushing the cement raw material to produce powder raw material; a suspension preheater for preheating and calcining the powdered raw material; a rotary kiln for burning the preheated and calcined powdered raw material into cement clinker; and A method for producing cement clinker using a cement calcination facility including a cement clinker cooler for cooling the cement clinker, The suspension preheater is A calciner for calcining the powdered raw material, a C-type air duct having three or more stages of cyclone dust collectors for collecting the powder raw material and a gas flow path connecting the three or more stages of cyclone dust collectors in sequence, through which the calciner combustion exhaust gas discharged from the calciner passes; A cyclone dust collector having three or more stages for collecting the powder raw material and a gas flow path for sequentially connecting the three or more stages of cyclone dust collectors, and a K-type air duct through which the kiln combustion exhaust gas discharged from the rotary kiln passes; a raw material conduit KI connecting the cyclone dust collector of the K system air duct and a gas flow path for supplying the calciner combustion exhaust gas to the cyclone dust collector of the C system air duct at the same stage as the cyclone dust collector of the K system air duct; A raw material conduit CI that connects the cyclone dust collector of the C system air duct and a gas flow path that supplies the kiln combustion exhaust gas to the cyclone dust collector of the K system air duct, which is one stage below the cyclone dust collector of the C system air duct; A raw material conduit K-II that connects the lowest cyclone dust collector in the K system air duct and the calciner; A raw material conduit C-II connecting the lowest cyclone dust collector of the C system air duct and the rotary kiln; a powder raw material supplying device that supplies the powder raw material to a topmost cyclone dust collector of at least one of the two air passages; At least one of the cyclone dust collectors at the lowest stage in the two air ducts and at least one of the cyclone dust collectors one stage above the lowest stage have a means for adjusting the dust collection efficiency of the powder raw material, The dust collection efficiency of the cyclone dust collector is adjusted by the adjustment means. That is it.

[0017] As described above, the cement calcination equipment described in Patent Document 1 introduces exhaust gas with a low concentration of carbon dioxide discharged from the preheater into equipment for recovering carbon dioxide having a regenerator and an absorber, which leads to an increase in the size of the equipment for recovering carbon dioxide.

[0018] Furthermore, in order to put the cement clinker production system described in Patent Document 3 into practice, it would be necessary to carry out large-scale modifications to the cement burning equipment.

[0019] Under these circumstances, the present inventors focused on the dust collection efficiency of the multiple cyclone dust collectors of the suspension preheater. The dust collection efficiency is generally set high in order to produce cement clinker more efficiently, and is not set in order to adjust the concentration of carbon dioxide in the flue gas. For this reason, Patent Documents 1 to 3 above make no mention whatsoever of adjusting the dust collection efficiency of the cyclone dust collector, or of the ability to adjust the amount (concentration) of carbon dioxide in the flue gas by such adjustment. Furthermore, there is no mention whatsoever of the ability to improve the amount of carbon dioxide recovered from the flue gas by adjusting the dust collection efficiency. The inventors deliberately adjusted the dust collection efficiency in order to adjust the amount (concentration) of carbon dioxide in the exhaust gas, and discovered that it is effective to adjust the dust collection efficiency of specific cyclone dust collectors among the multiple cyclone dust collectors that a suspension preheater has, i.e., the lowest cyclone dust collector or the cyclone dust collector one level above the lowest cyclone dust collector. As a result, it has become possible to adjust the amount of carbon dioxide contained in the combustion exhaust gas generated in a cement calcination facility without carrying out large-scale modifications to the facility.

[0020] Hereinafter, the method for producing cement clinker of this embodiment will be described with reference to Fig. 1. Fig. 1 is a schematic diagram showing a preferred embodiment of cement burning equipment used in the method for producing cement clinker of this embodiment. FIG. 1 shows that the cement calcination facility includes a suspension preheater that preheats and calcines powdered raw materials, a rotary kiln that calcines the powdered raw materials preheated and calcined in the suspension preheater to produce cement clinker, and a clinker cooler that cools the cement clinker.

[0021] (Suspension preheater) The suspension preheater used in the manufacturing method of this embodiment has three or more stages of cyclone dust collectors (four stages of cyclone dust collectors: C1-C4 and K1-K4) for collecting powder raw materials, and a gas flow path (gas flow paths C0a-C4a and K0a-K4a) that sequentially connects the three or more stages of cyclone dust collectors, and has two air passages (C-system flow path and K-system flow path) through which different exhaust gases pass independently, as shown in Fig. 1. Here, the C-system flow path is used for calciner combustion exhaust gas, which is exhaust gas discharged by burning fuel in a calciner, and the K-system flow path is used for kiln combustion exhaust gas, which is exhaust gas discharged by burning fuel in a rotary kiln.

[0022] In addition, in FIG. 1, the calciner combustion exhaust gas and the kiln combustion exhaust gas, which are different from each other, pass independently through the C system air duct and the K system air duct. The calciner combustion exhaust gas passes through the cyclone collector C1 at the lowest stage through the cyclone collector C4 at the highest stage, in order, via gas flow paths (C0a to C4a). The kiln combustion exhaust gas passes through the cyclone collector K1 at the lowest stage through the cyclone collector K4 at the highest stage, in order, via gas flow paths (K1a to K4a).

[0023] As described above, the suspension preheater has two air passages through which different exhaust gases pass independently, a raw material conduit, a powder raw material feeder, and a means for adjusting the dust collection efficiency of a given powder raw material. The calciner is also provided. By providing the calciner, the powder raw material can be preheated and calcined more efficiently.

[0024] The suspension preheater may have three or more stages of cyclone collectors, and may have, for example, four or more stages of cyclone collectors as shown in Fig. 1. From the viewpoint of more efficiently recovering heat from the exhaust gas, four or more stages are preferable.

[0025] FIG. 1 shows raw material conduits including raw material conduit KI (K2b-K4b in FIG. 1) connecting a cyclone dust collector in a K-line air duct to a gas flow path for supplying calciner combustion exhaust gas to a cyclone dust collector in a C-line air duct at the same stage as the cyclone dust collector in the K-line air duct, and raw material conduit K-II (K1b in FIG. 1) connecting a cyclone dust collector at the lowest stage of the K-line air duct to a calciner. It is shown that the rotary kiln has a raw material conduit CI (C2b to C4b in Figure 1) that connects the cyclone dust collector in the air duct to a gas flow path that supplies kiln combustion exhaust gas to a cyclone dust collector in the K-line air duct one level below the cyclone dust collector in the C-line air duct, and a raw material conduit C-II (C1b in Figure 1) that connects the cyclone dust collector at the bottom level of the C-line air duct to the rotary kiln. Here, if the cyclone dust collector in the K-line air duct is K3, the cyclone dust collector in the C-line air duct at the same stage as the cyclone dust collector K3 in the K-line air duct is C3, and the raw material conduit connected to the gas flow path C2a that supplies the calciner combustion exhaust gas to this cyclone dust collector C3 is K3b. Also, for example, if the cyclone dust collector in the C-line air duct is C3, the cyclone dust collector in the K-line air duct one stage below the cyclone dust collector C3 in the C-line air duct is K2, and the raw material conduit connected to the gas flow path K1a that supplies the kiln combustion exhaust gas to this cyclone dust collector K2 is C3b.

[0026] The cement raw material that has passed through the drying and grinding device is supplied from a powder raw material feeder (described later) to a suspension preheater, more specifically, from the powder raw material feeder to the cyclone dust collector at the top of the suspension preheater. In Fig. 1, the powder raw material is supplied from the powder raw material feeder of the K system to the cyclone dust collector K4 at the top of the K system air duct, and from the powder raw material feeder of the C system to the cyclone dust collector C4 at the top of the C system air duct. The powdered raw material supplied from the K-system powdered raw material supplying machine passes through the cyclone dust collector K4, raw material conduit K4b, gas flow path C3a, cyclone dust collector C4, raw material conduit C4b, gas flow path K2a, cyclone dust collector K3, raw material conduit K3b, gas flow path C2a, cyclone dust collector C3, raw material conduit C3b, gas flow path K1a, cyclone dust collector K2, raw material conduit K2b, gas flow path C1a, cyclone dust collector C2, raw material conduit C2b, gas flow path K0a, cyclone dust collector K1, raw material conduit K1b, calciner, gas flow path C0a, cyclone dust collector C1, and raw material conduit C1b in this order, where it is preheated and calcined and then supplied to the rotary kiln. In addition, the powdered raw material supplied from the powdered raw material supply machine of the C system is supplied to a cyclone dust collector C4, and together with the powdered raw material supplied from the powdered raw material supply machine of the K system, passes through raw material conduit C4b and raw material conduit C1b, is preheated and calcined, and is supplied to the rotary kiln.

[0027] In this way, the powdered raw material supplied to the suspension preheater moves alternately from the upper to lower cyclone collectors of the C-system air passage and the K-system air passage, which are different from each other, and is supplied to the rotary kiln after passing through all of the cyclone collectors. The powdered raw material moving from the top to the bottom cyclone collector comes into contact with the combustion exhaust gas (calciner combustion exhaust gas and kiln combustion exhaust gas) moving in the air passage in the opposite direction, that is, from the bottom cyclone collector to the top cyclone collector, and can be efficiently preheated and calcined.

[0028] The powder raw material feeder is a device that feeds the powder raw material obtained in the drying and grinding device to the uppermost cyclone dust collector of at least one of the two air ducts, the C-line air duct and the K-line air duct. In Fig. 1, the powder raw material feeder is provided for both the C-line air duct and the K-line air duct. That is, as the powder raw material feeder, a C-line powder raw material feeder that feeds the powder raw material to the uppermost cyclone dust collector of the C-line air duct and a K-line powder raw material feeder that feeds the powder raw material to the uppermost cyclone dust collector of the K-line air duct are provided.

[0029] More specifically, the powdered raw materials from the powdered raw material feeder are supplied into a gas flow path connected to a cyclone dust collector that is the supply destination. Taking the powdered raw materials in the K system as an example, the supply of the powdered raw materials in the K system is supplied to a gas flow path K3a connected to the cyclone dust collector K4 that is the supply destination of the kiln combustion exhaust gas from the cyclone dust collector K3. Also, taking the powdered raw materials in the C system as an example, the supply of the powdered raw materials in the C system is supplied to a gas flow path C3a connected to the cyclone dust collector C4 that is the supply destination of the calciner combustion exhaust gas from the cyclone dust collector C3.

[0030] The powder raw material feeder may be provided so as to supply the powder raw material to the uppermost cyclone dust collector of at least one of the two air passages, the C-line air passage and the K-line air passage. In the case of FIG. 1, since the powder raw material can pass through all the cyclone dust collectors, it is sufficient to provide a powder raw material feeder that supplies at least the uppermost cyclone dust collector K4 of the K-line air passage. Also, as shown in FIG. 1, two powder raw material feeders, such as a C-line powder raw material feeder and a K-line powder raw material feeder, may be provided so as to supply the powder raw material to the uppermost cyclone dust collectors C4 and K4 of the C-line air passage and the K-line air passage, which are both air passages of the two air passages. In the manufacturing method of this embodiment, it is preferable to provide the powder raw material to all of the two air passages from the viewpoint of more stable supply of the powder raw material and more efficient preheating and calcination.

[0031] In the suspension preheater, at least one of the cyclone dust collectors at the lowest stage of the two air passages, the C-line air passage and the K-line air passage, and at least one of the cyclone dust collectors one stage above the lowest stage, is adjusted in dust collection efficiency using adjustment means for the dust collection efficiency of the powder raw material possessed by these cyclone dust collectors. By effectively utilizing the adjustment means in these cyclone dust collectors to adjust the dust collection efficiency, it becomes possible to adjust the amount of carbon dioxide in the combustion exhaust gas. Here, the lowest cyclone dust collector in the C-line air duct corresponds to the cyclone dust collector C1 in Fig. 1, and the lowest cyclone dust collector in the C-line air duct corresponds to the cyclone dust collector K1 in Fig. 1. The cyclone dust collector one level above the lowest level in the C-line air duct corresponds to the cyclone dust collector C2 in Fig. 1, and the cyclone dust collector one level above the lowest level in the K-line air duct corresponds to the cyclone dust collector K2 in Fig. 1.

[0032] The lowest cyclone dust collector whose dust collection efficiency is adjusted using an adjustment means may be at least one of the cyclone dust collectors arranged at the lowest stage of the C system air duct and the K system air duct. Considering the ease of adjusting the amount of carbon dioxide contained in the combustion exhaust gas, it is preferable to adjust the dust collection efficiency using the adjustment means of the lowest cyclone dust collector in the C system air duct, cyclone dust collector C1 in Figure 1, and it is more preferable to adjust the dust collection efficiency using the adjustment means of multiple, or even all, of the lowest cyclone dust collectors (both cyclone dust collectors C1 and K1 in Figure 1).

[0033] The cyclone dust collector one level above the bottommost level, whose dust collection efficiency is adjusted using an adjustment means, may be at least one cyclone dust collector arranged in the one level above. Considering the ease of adjusting the amount of carbon dioxide in the combustion exhaust gas, it is preferable to adjust the dust collection efficiency using an adjustment means of the cyclone dust collector in the K system air duct, cyclone dust collector K2 in Figure 1, and it is more preferable to adjust the dust collection efficiency using an adjustment means of the cyclone dust collector one level above the bottommost level in each of the C system air duct and the K system air duct (this applies to both cyclone dust collectors C2 and K2 in Figure 1).

[0034] The above describes a case where the dust collection efficiency is adjusted using an adjustment means in one of the cyclone dust collectors in either the lowest stage or the stage one above the lowest stage in the C system air duct and the K system air duct. However, as already mentioned, it is preferable to adjust the dust collection efficiency using adjustment means in both of the cyclone dust collectors in the lowest stage and the stage one above the lowest stage in the C system air duct and the K system air duct.

[0035] It is more preferable to adjust the dust collection efficiency of each of the four cyclone dust collectors at the lowest stage and the stage one stage above the lowest stage, which the C system air duct and the K system air duct have. Furthermore, the dust collection efficiency of these four cyclone dust collectors only needs to be such that the amount of carbon dioxide in the combustion exhaust gas is a predetermined amount, and there is no problem if the dust collection efficiency becomes the same value before and after the dust collection efficiency adjustment, or if the dust collection efficiency remains the same value without adjustment. In other words, in order to obtain a predetermined amount of carbon dioxide in the combustion exhaust gas, the dust collection efficiency of one to four of these four cyclone dust collectors can be adjusted.

[0036] When adjusting the dust collection efficiency using the adjustment means of both of the cyclone dust collectors (cyclone dust collectors C1 and K1) at the lowest stage of the two cyclone dust collectors in the C system air duct and the K system air duct, and both of the cyclone dust collectors (cyclone dust collectors C2 and K2) at the stage one level above the lowest stage, how the amount of carbon dioxide in the combustion exhaust gas can be adjusted will be described in more detail using a preferred embodiment as an example.

[0037] (Powdered raw materials in cyclone dust collector C1: Decarbonation reaction) The calcium carbonate contained in the powdered raw material is heated in a calciner at a high temperature, preferably at 800 to 900° C., whereby the following decarbonation reaction proceeds to produce calcium oxide. CaCO3 → CaO + CO2 The powdered raw material decarbonated in the calciner is entrained in the calciner combustion exhaust gas and is supplied to the cyclone dust collector C1, which is the lowest cyclone dust collector in the air passage C, via the gas flow path C0a. Here, the decarbonation rate of the powdered raw material is about 90%, and the decarbonation rate is a rate expressed by the following formula.

[0038] Decarboxylation rate (%)=(Ca0-Ca1) / Ca0×100 Ca0: The amount of calcium carbonate contained in the powdered raw material fed into the suspension preheater (ton / h). Ca1: The amount of calcium carbonate contained in the powdered raw material in the cyclone dust collector C1 (ton / h). Here, the powder raw material fed into the suspension preheater corresponds to the powder raw material fed from the C-based powder raw material feeder and the K-based powder raw material feeder in FIG.

[0039] (Powdered raw materials in cyclone dust collector K2: Carbonation reaction) The powdered raw material containing calcium oxide decarbonated in the cyclone dust collector C1, which is the cyclone dust collector at the lowest stage of the air duct, is supplied to an atmosphere of combustion exhaust gas at a lower temperature than the cyclone dust collector C1, preferably to an atmosphere of combustion exhaust gas in the K-system air duct. As a result, the carbon dioxide contained in the combustion exhaust gas reacts with the calcium oxide contained in the powdered raw material, and the following carbonation reaction proceeds to produce calcium carbonate. CaO+CO2→CaCO3

[0040] (Dust collection efficiency in cyclone dust collectors) The powdered raw material that is entrained in the combustion exhaust gases from the calciner combustion exhaust gas and the kiln combustion exhaust gas and supplied to the cyclone dust collector is captured by inertial force and discharged from the raw material conduit (hereinafter also referred to as "collected raw material"). On the other hand, the powdered raw material that is not captured (hereinafter also referred to as "scattered raw material") is entrained in the combustion exhaust gas and discharged from the gas flow path, and is supplied to a higher-stage cyclone dust collector. Here, the dust collection efficiency of the cyclone dust collector is an efficiency calculated by the following formula. Dust collection efficiency (%) = collected material / (collected material + scattered material) x 100

[0041] The dust collection efficiency can be adjusted by a dust collection efficiency adjustment means provided in the cyclone dust collector, and the amount of the collected raw material and the scattered raw material can be increased or decreased by adjusting the dust collection efficiency. Furthermore, as described below, by adjusting the dust collection efficiency, the decarbonation and carbonation can be adjusted, and therefore the amount of carbon dioxide contained in the combustion exhaust gas can be adjusted.

[0042] (Powdered raw materials in cyclone dust collector C1: Behavior of powdered raw materials) Powdered raw material containing calcium oxide is supplied from the calciner through a gas flow path C0a to a cyclone dust collector C1 at the bottom of the air passage, where it is separated into collected raw material and scattered raw material. The collected raw material is supplied to a rotary kiln through a raw material conduit C1b, where it is completely decarbonated and burned to become clinker.

[0043] On the other hand, the scattered raw material from the cyclone dust collector C1, which is the cyclone dust collector at the bottom of the air duct, is entrained by the calciner combustion exhaust gas and passes through the gas flow path C1a, where it joins with the collected raw material in the cyclone dust collector K2 in the raw material conduit K2b and is supplied to the cyclone dust collector C2, which is one level above the bottom of the C-line air duct. Considering the need to adjust the amount of carbon dioxide contained in the combustion exhaust gas and further to adjust the amount of carbon dioxide contained in the calciner combustion exhaust gas in the C system air duct so as to increase it, it is preferable to adjust and reduce the dust collection efficiency of the cyclone dust collector C1 and transfer the scattered raw material containing a larger amount of calcium oxide to the cyclone dust collector C2.

[0044] The dust collection efficiency of the lowest cyclone dust collector (preferably cyclone dust collector C1) is preferably 50% or more, more preferably 55% or more, and the upper limit is preferably 80% or less, more preferably 70% or less, and further preferably 65% ​​or less. By setting the dust collection efficiency of the cyclone dust collector C1, which is the lowest cyclone dust collector, to 50% or more, the collected raw material can be efficiently supplied to the rotary kiln, and cement clinker can be efficiently produced. On the other hand, by setting the dust collection efficiency to 80% or less, the scattered raw material containing calcium oxide can be increased, and the carbon dioxide contained in the kiln combustion exhaust gas can be efficiently used for carbonation.

[0045] (About powdered raw materials in cyclone dust collector C2: Behavior of powdered raw materials) The powdered raw material supplied to the cyclone dust collector C2, which is one level above the bottom level of the air duct, is separated into collected raw material and scattered raw material. The collected raw material is supplied to the cyclone dust collector K1, which is the bottom level of the K air duct, via the raw material conduit C2b and accompanied by the kiln combustion exhaust gas passing through the gas flow path K0a.

[0046] On the other hand, the scattered raw material from cyclone dust collector C2, which is the cyclone dust collector one level above the bottom of the air duct, is entrained by the calciner combustion exhaust gas and passes through gas flow path C2a, where it joins with the collected raw material in cyclone dust collector K3 in raw material conduit K3b and is supplied to cyclone dust collector C3, which is two levels above the bottom of the C-line air duct. Considering the need to adjust the amount of carbon dioxide contained in the combustion exhaust gas and to increase the amount of carbon dioxide contained in the calciner combustion exhaust gas in the C-line air passage, it is preferable to adjust and increase the dust collection efficiency of the cyclone dust collector C2. By adjusting in this way, more raw material containing calcium oxide can be supplied to the cyclone dust collector K1 at the bottom of the K-line air passage, so that the carbon dioxide contained in the kiln combustion exhaust gas can be used more efficiently to carbonate calcium oxide. In addition, the amount of raw material scattered to the cyclone dust collector C3 one level above can be reduced, and carbonation in the cyclone dust collector C3 can be suppressed.

[0047] The dust collection efficiency of the cyclone dust collector one level above the lowest level (preferably cyclone dust collector C2) is preferably 85% or more, more preferably 90% or more. By making the dust collection efficiency of the cyclone dust collector one level above the lowest level 85% or more, a larger amount of collected raw material containing calcium oxide can be supplied to the cyclone dust collector K1 at the bottom of the K system air duct, and carbon dioxide contained in the kiln combustion exhaust gas can be used more efficiently to carbonate calcium oxide.

[0048] (About powdered raw materials in the cyclone dust collector K1: Behavior of powdered raw materials) By adjusting the cyclone dust collectors C1 and C2, the powdered raw material containing calcium oxide supplied to the cyclone dust collector K1, which is the cyclone dust collector at the bottom of the air passage, is separated into a collected raw material and a scattered raw material. The collected raw material is supplied to a calciner through a raw material conduit K1b.

[0049] Meanwhile, the scattered raw materials from the cyclone dust collector K1 at the bottom of the air duct are entrained by the kiln combustion exhaust gas and travel through the gas flow path K1a to join with the collected raw materials in the cyclone dust collector C3 in the raw material conduit C3b, and are supplied to the cyclone dust collector K2, which is one level above the bottom of the K system air duct. In the manufacturing method of this embodiment, it is preferable to adjust and reduce the dust collection efficiency of the cyclone dust collector K1. By adjusting in this way, a powder raw material containing a larger amount of calcium oxide can be supplied as a scattered raw material to the cyclone dust collector K2 in the next upper stage, so that the carbonation reaction can be promoted and the amount of carbon dioxide contained in the calciner combustion exhaust gas in the C system air duct can be adjusted to be larger.

[0050] The dust collection efficiency of the lowest cyclone dust collector (preferably cyclone dust collector K1) is preferably 50% or more, more preferably 55% or more, and the upper limit is preferably 80% or less, more preferably 70% or less, and even more preferably 65% ​​or less. By setting the dust collection efficiency of the cyclone dust collector K1, which is the lowest cyclone dust collector, to 50% or more, the collected raw material can be efficiently supplied to the calciner, and the decarbonation of the powder raw material in the calciner can be promoted. On the other hand, by setting the dust collection efficiency to 80% or less, the scattered raw material containing calcium oxide can be increased, and a powder raw material containing more calcium oxide can be supplied to the cyclone dust collector K2, which is the cyclone dust collector one level above the lowest level, and the carbon dioxide contained in the kiln combustion exhaust gas can be efficiently used for carbonation.

[0051] (On powdered raw materials in the cyclone dust collector K2: Behavior of powdered raw materials) By adjusting the cyclone dust collectors (cyclone dust collectors C1 and K1) at the bottom of the above air duct and the cyclone dust collector C2 one level above the bottom level, powdered raw material containing more calcium oxide is supplied to the cyclone dust collector K2 one level above the other bottom level, as described above. By supplying powdered raw material containing more calcium oxide to the cyclone dust collector K2 one level above the other bottom level from the bottom level in the K-system air duct, the calcium oxide contained in the powdered raw material is carbonized by the carbon dioxide contained in the kiln combustion exhaust gas to produce calcium carbonate. This makes it possible to reduce the amount of carbon dioxide contained in the kiln combustion exhaust gas, and the more the amount of calcium oxide contained in the powdered raw material is increased, the more the amount of carbon dioxide can be reduced.

[0052] The temperature of the kiln combustion exhaust gas passing through the cyclone dust collector K2 one stage above the bottom stage of the air passage (i.e., the heating temperature of the powdered raw material in the cyclone dust collector K2) is preferably 550°C or higher, more preferably 600°C or higher, and even more preferably 650°C or higher, with the upper limit being preferably 700°C or lower. If the temperature of the kiln combustion exhaust gas passing through the cyclone dust collector K2 is 550°C or higher, the preheating of the powdered raw material can be promoted, and if it is 700°C or lower, the carbonation of calcium oxide can be promoted, making it possible to reduce the amount of carbon dioxide in the kiln combustion exhaust gas.

[0053] In order to reduce the temperature of the kiln combustion exhaust gas passing through the cyclone dust collector K2, which is one stage above the lowest stage of the air passage, water or water-containing waste may be supplied to the combustion exhaust gas passing through at least one of the gas passages K0a and K1a on the rotary kiln side of the cyclone dust collector K2, more preferably to the combustion exhaust gas passing through the gas passage K0a, and it is particularly preferable to supply water-containing waste to the combustion exhaust gas passing through the gas passage K0a. Here, by supplying water-containing waste to the gas passage K0a, not only can the temperature of the kiln combustion exhaust gas passing through the cyclone dust collector K2 be adjusted, but also the water-containing waste can be introduced into the rotary kiln, thereby preventing clogging of the cyclone dust collector. Representative examples of the water-containing waste include organic sludge such as sewage sludge, and various types of wastewater such as waste acid and waste alkali.

[0054] In addition, in order to raise the temperature of the kiln combustion exhaust gas passing through the cyclone dust collector K2, which is one level above the lowest level in the air duct, combustible waste may be supplied to the combustion exhaust gas passing through at least one of the gas flow paths K0a and K1a on the rotary kiln side of the cyclone dust collector K2, more preferably to the combustion exhaust gas passing through the gas flow path K0a. Representative examples of combustible waste include oil-containing sludge such as waste clay, waste oil, waste plastics, and the like.

[0055] Powdered raw material containing calcium oxide supplied to the cyclone dust collector K2, which is the cyclone dust collector one level above the bottom level, becomes powdered raw material containing calcium carbonate through a carbonation reaction of calcium oxide, and is separated into collected raw material and scattered raw material. The collected raw material passes through the raw material conduit K2b, passes through the gas flow path C1a, or is entrained in the furnace combustion exhaust gas, and is supplied to the cyclone dust collector C2, which is one level above the bottom level of the C system air duct.

[0056] On the other hand, the raw material scattered from the cyclone dust collector K2, which is the cyclone dust collector one level above the bottom of the air duct, into the gas flow path K2a is merged with the collected raw material in the cyclone dust collector C4 which is supplied to the gas flow path K2a via the raw material conduit C4b, and is supplied to the cyclone dust collector K3, which is two levels above the bottom of the K system air duct. In the manufacturing method of this embodiment, it is preferable to adjust and increase the dust collection efficiency of the cyclone dust collector K2. By adjusting in this way, the powdery raw material containing calcium carbonate can be supplied to the calciner as a collected raw material via the cyclone dust collector C2 one level above the lowest level in the air passage, so that the amount of carbon dioxide contained in the calciner combustion exhaust gas can be adjusted to be increased.

[0057] The dust collection efficiency of the cyclone dust collector one level above the lowest level (preferably cyclone dust collector K2) is preferably 85% or more, more preferably 90% or more. By setting the dust collection efficiency of the cyclone dust collector K2 one level above the lowest level to 85% or more, the exhaust gas from the calciner can be supplied to the calciner via the cyclone dust collector C2 one level above the lowest level in the C system air duct, making it possible to adjust the amount of carbon dioxide contained in the calciner combustion exhaust gas to be large.

[0058] As described above, in order to set the dust collection efficiency of the cyclone dust collector C2 high, most of the powder raw material fed to the cyclone dust collector C2 is fed to the cyclone dust collector K1 as collected raw material, and the collected raw material in the cyclone dust collector K1 is fed to the calciner. The scattered raw material in the cyclone dust collector K1 is fed to the calciner while circulating through the gas flow path K1a, raw material conduit C3b, cyclone dust collector K2, raw material conduit K2b, gas flow path C1a, cyclone dust collector C2, raw material conduit C2b, gas flow path K0a, and cyclone dust collector K1.

[0059] In addition, the powdered raw material supplied to the calciner contains a large amount of calcium carbonate, which is a result of the carbonation of calcium oxide, and is decarbonated together with the calcium carbonate contained in the powdered raw material newly supplied to the suspension preheater to generate calcium oxide and carbon dioxide. As a result, the carbon dioxide contained in the kiln flue gas is adsorbed by the carbonation of calcium oxide and can be released into the calciner flue gas in the calciner. In this way, the amount of carbon dioxide in the calciner flue gas can be increased while reducing the amount of carbon dioxide contained in the kiln flue gas, i.e., the carbon dioxide contained in the kiln flue gas can be transferred to the calciner flue gas.

[0060] (Adjusting the amount of carbon dioxide in the combustion exhaust gas by adjusting the dust collection efficiency) According to the manufacturing method of this embodiment, at least one of the cyclone dust collectors at the lowest stage of the two air passages of the suspension preheater and at least one of the cyclone dust collectors one stage above the lowest stage have a means for adjusting the dust collection efficiency of the powder raw material, and this adjustment means adjusts the dust collection efficiency of the cyclone dust collector. As a result, as explained above, it is possible to adjust the amount of carbon dioxide contained in the combustion exhaust gas. Depending on the method of adjustment, it is also possible to increase the amount of carbon dioxide in the calciner combustion exhaust gas, for example. Below, we will explain an embodiment of a method for adjusting the amount of carbon dioxide in the combustion exhaust gas by adjusting the dust collection efficiency, and more specifically, how to adjust the amount of carbon dioxide contained in the combustion exhaust gas by increasing or decreasing the dust collection efficiency in the lowest cyclone dust collectors C1 and K1 and the cyclone dust collectors C2 and K2 one level above the lowest level.

[0061] According to the manufacturing method of this embodiment, the dust collection efficiency of the cyclone dust collector C1, which is the lowest cyclone dust collector in the air passage, is adjusted to be reduced, so that the amount of scattered raw material in the cyclone dust collector C1 can be increased. Therefore, the powder raw material containing more calcium oxide is supplied from the lowest cyclone dust collector to the cyclone dust collector K2 via the cyclone dust collector C2 and cyclone dust collector K1, which are the next higher cyclone dust collectors, and the amount of carbon dioxide contained in the kiln combustion exhaust gas that is adsorbed as calcium oxide by carbonation can be increased.

[0062] Conversely, by adjusting the dust collection efficiency of the cyclone dust collector C1 to increase, the amount of raw material collected in the cyclone dust collector C1 can be increased. This allows the amount of powdered raw material containing calcium oxide to be reduced to the cyclone dust collector K2, and therefore the amount of carbon dioxide contained in the kiln combustion exhaust gas passing through the cyclone dust collector K2 that is adsorbed as calcium carbonate can be reduced. In adjusting the amount of carbon dioxide contained in the combustion exhaust gas, the dust collection efficiency of the cyclone dust collector may be adjusted to an arbitrary value according to the target amount of carbon dioxide adsorption. The same applies to the adjustment of the dust collection efficiency described below.

[0063] By adjusting the dust collection efficiency of the cyclone dust collector C2 to be higher, the amount of raw material collected in the cyclone dust collector C2 can be increased, so that a powdered raw material containing more calcium oxide can be supplied to the cyclone dust collector K2 via the cyclone dust collector K1 as the raw material to be collected, and the amount of carbon dioxide contained in the kiln combustion exhaust gas that is adsorbed as calcium oxide by carbonation can be increased. Conversely, by adjusting the dust collection efficiency of the cyclone dust collector C2 to be reduced, the amount of raw material collected in the cyclone dust collector C2 can be reduced. This reduces the amount of raw material collected, which is a powder raw material containing a larger amount of calcium oxide, and therefore reduces the amount of carbon dioxide contained in the kiln combustion exhaust gas passing through the cyclone dust collector K2 that is adsorbed as calcium oxide.

[0064] By adjusting the dust collection efficiency of the cyclone dust collector K1 to be reduced, the amount of scattered raw material in the cyclone dust collector K1 can be increased. This allows a powdered raw material containing more calcium oxide to be supplied to the cyclone dust collector K2 as scattered raw material, and increases the amount of carbon dioxide contained in the kiln combustion exhaust gas that is adsorbed as calcium oxide by carbonation. Conversely, by adjusting the dust collection efficiency of the cyclone dust collector K1 to increase, the amount of scattered raw material in the cyclone dust collector K1 can be reduced. This reduces the amount of collected raw material, which is a powder raw material containing a larger amount of calcium oxide, and therefore reduces the amount of carbon dioxide contained in the kiln combustion exhaust gas passing through the cyclone dust collector K2 that is adsorbed as calcium oxide.

[0065] By adjusting the dust collection efficiency of the cyclone dust collector K2 to be higher, the amount of raw material collected in the cyclone dust collector K2 can be increased. As a result, a powdered raw material containing calcium carbonate obtained by carbonating calcium oxide can be supplied to the calciner via the cyclone dust collectors C2 and K1 as the raw material. In the calciner, calcium carbonate is decarbonated to calcium oxide and carbon dioxide, and the amount of carbon dioxide released into the calciner combustion exhaust gas can be increased. Conversely, by adjusting the dust collection efficiency of the cyclone dust collector K2 to be reduced, the amount of raw material collected in the cyclone dust collector K2 can be reduced. This reduces the amount of raw material collected, which is a powder raw material containing calcium carbonate, and therefore the amount of carbon dioxide released into the calciner combustion exhaust gas can be reduced.

[0066] According to the manufacturing method of this embodiment, the dust collection efficiency of at least one of the cyclone dust collectors at the lowest stage and at least one of the cyclone dust collectors one stage above the lowest stage, each having a means for adjusting the dust collection efficiency of the powder raw material, is adjusted using the adjustment means. By these adjustments, as described above, the amount of collected raw material and scattered raw material in the cyclone dust collectors can be adjusted, and the amount of carbon dioxide contained in the combustion exhaust gas discharged from the suspension preheater, i.e., the kiln combustion exhaust gas and the calciner combustion exhaust gas, can be adjusted, and preferably the carbon dioxide contained in the kiln combustion exhaust gas can be moved to the calciner combustion exhaust gas to increase the amount of carbon dioxide contained in the calciner combustion exhaust gas.

[0067] (Impact on cement clinker production volume) The amount of powdered raw material circulating through the suspension preheater changes by adjusting the amount of collected raw material and scattered raw material by adjusting the dust collection efficiency of the cyclone dust collector, but the powdered raw material supplied from the powdered raw material supplying machine passes through and / or circulates through the two air passages of the suspension preheater alternately, is supplied to the calciner, and then is introduced into the rotary kiln. Therefore, it is possible to adjust the amount of carbon dioxide contained in the combustion exhaust gas without changing the production amount of cement clinker.

[0068] In this way, by adjusting the dust collection efficiency of at least one of the cyclone dust collectors in the lowest stage of the two air ducts of the suspension preheater and at least one of the cyclone dust collectors one stage above the lowest stage, it is possible to adjust the amount of carbon dioxide contained in the combustion exhaust gas discharged from the suspension preheater without changing the production amount of cement clinker.

[0069] A specific example of a means for adjusting the dust collection efficiency in a cyclone dust collector is a method for adjusting the flow velocity of the exhaust gas in the gas flow passage supplied to the cyclone dust collector. One method for adjusting the flow velocity of the exhaust gas is to adjust the cross-sectional area of ​​the gas flow passage. By increasing the cross-sectional area, the gas flow velocity can be slowed down, and by decreasing the cross-sectional area, the gas flow velocity can be increased. The flow velocity of the exhaust gas and the dust collection efficiency are proportional to each other within a certain range, and the faster the flow velocity of the exhaust gas, the higher the dust collection efficiency. Examples of methods for adjusting the cross-sectional area of ​​the exhaust gas flow velocity include changing the thickness of the lining fireproof material of the gas flow passage and replacing the gas flow passage duct. These methods are merely examples, and there are no limitations on the method as long as the flow velocity of the exhaust gas can be adjusted, and other methods can also be used.

[0070] Another method for adjusting the dust collection efficiency of a cyclone dust collector is to adjust the insertion rate of the inner cylinder of the cyclone dust collector. In this case, within a certain range, the insertion rate of the inner cylinder and the dust collection efficiency are proportional to each other, and the dust collection efficiency can be increased by increasing the insertion rate of the inner cylinder, and the dust collection efficiency can be decreased by decreasing the insertion rate of the inner cylinder. The above adjustment methods may be used alone or in combination.

[0071] (Carbon dioxide capture equipment) In the production method of this embodiment, when carbon dioxide is recovered from the exhaust gas that has passed through the cyclone dust collector, it is preferable to use a carbon dioxide recovery facility, and it is more preferable to recover carbon dioxide from the calciner combustion exhaust gas using a carbon dioxide recovery facility. The calciner flue gas contains a large amount of carbon dioxide of non-energy origin generated by decarbonation of calcium carbonate contained in the powdered raw material, in addition to carbon dioxide of energy origin generated by combustion of fuel. In this case, the calciner flue gas contains a large amount of carbon dioxide compared to the amount of carbon dioxide contained in the kiln flue gas, so the concentration of carbon dioxide is high. Therefore, it is easier to separate and recover carbon dioxide from the calciner flue gas than from the kiln flue gas. Also, as described above, by adjusting the dust collection efficiency with the adjustment means of the cyclone dust collector, the amount of carbon dioxide contained in the calciner flue gas is increased, making it easier to separate and recover carbon dioxide. In this way, by using the carbon dioxide capture equipment to capture carbon dioxide from the calciner combustion exhaust gas discharged from the suspension preheater, it is possible to capture a larger amount of carbon dioxide more efficiently.

[0072] There are no particular limitations on the type of carbon dioxide recovery equipment as long as it can recover carbon dioxide from exhaust gas, and it can be appropriately selected from, for example, a liquid absorption type, a membrane separation type, a solid adsorption type, a compression liquefaction recovery type, and the like.

[0073] (Drying cement raw materials) As described above, the amount of carbon dioxide contained in the kiln flue gas can be reduced, and the kiln flue gas discharged from the suspension preheater can be used to dry the cement raw materials. This allows the thermal energy of the flue gas to be recovered more efficiently, improving the thermal efficiency of the production method of this embodiment. As the exhaust gas used for drying the cement raw materials, in addition to the kiln combustion exhaust gas, the clinker cooler exhaust gas discharged from the clinker cooler can also be used. In this way, according to the manufacturing method of this embodiment, it is possible to improve the thermal efficiency while suppressing the amount of carbon dioxide released into the atmosphere.

[0074] Examples of drying and crushing devices that dry and crush cement raw materials to produce powder raw materials include drying and crushing devices that combine a drying device such as a rotary dryer with a crushing device such as a tube mill, and drying and crushing devices that can perform drying and crushing simultaneously. When a drying and crushing device that combines a drying device and a crushing device is used, the exhaust gas used to dry the cement raw materials can be supplied to the drying device, and when a drying and crushing device is used, the exhaust gas can be supplied to the drying and crushing device.

[0075] (Other devices) The configuration of the suspension preheater and the method of adjusting the same have been described above in relation to the manufacturing method of this embodiment. The cement burning equipment used in the manufacturing method of this embodiment includes a drying and crushing device and a rotary kiln in addition to the suspension preheater. Conventional devices can be used for the drying and crushing device and the rotary kiln.

[0076] [Cement baking equipment] The cement burning equipment of this embodiment is A drying and crushing device for drying and crushing the cement raw material to produce powder raw material; a suspension preheater for preheating and calcining the powdered raw material; a rotary kiln for burning the preheated and calcined powdered raw material into cement clinker; and A cement burning facility including a cement clinker cooler for cooling the cement clinker, The suspension preheater is A calciner for calcining the powdered raw material, a C-type air duct having three or more stages of cyclone dust collectors for collecting the powder raw material and a gas flow path connecting the three or more stages of cyclone dust collectors in sequence, through which the calciner combustion exhaust gas discharged from the calciner passes; A cyclone dust collector having three or more stages for collecting the powder raw material and a gas flow path for sequentially connecting the three or more stages of cyclone dust collectors, and a K-type air duct through which the kiln combustion exhaust gas discharged from the rotary kiln passes; a raw material conduit KI connecting the cyclone dust collector of the K system air duct and a gas flow path for supplying the calciner combustion exhaust gas to the cyclone dust collector of the C system air duct at the same stage as the cyclone dust collector of the K system air duct; A raw material conduit CI that connects the cyclone dust collector of the C system air duct and a gas flow path that supplies the kiln combustion exhaust gas to the cyclone dust collector of the K system air duct, which is one stage below the cyclone dust collector of the C system air duct; A raw material conduit K-II that connects the lowest cyclone dust collector in the K system air duct and the calciner; A raw material conduit C-II connecting the lowest cyclone dust collector of the C system air duct and the rotary kiln; a powder raw material supplying device that supplies the powder raw material to a topmost cyclone dust collector of at least one of the two air passages; At least one of the cyclone dust collectors at the lowest stage in the two air passages and at least one of the cyclone dust collectors one stage above the lowest stage have a means for adjusting the dust collection efficiency of the powder raw material. That is it.

[0077] In the cement burning equipment of this embodiment, the drying and crushing device, the suspension preheater, and the rotary kiln are as described in the above-mentioned cement clinker manufacturing method. In addition, for the suspension preheater, the cyclone dust collector, the two air ducts having the gas flow passages, the raw material conduit, and the adjustment means of the cyclone dust collector are also as described in the above-mentioned cement clinker manufacturing method. Therefore, the method for producing cement clinker according to the present embodiment can be easily carried out by using the cement burning equipment according to the present embodiment. EXAMPLES

[0078] The present invention will now be described in detail with reference to examples, but the present invention is not limited to these examples in any way.

[0079] Comparative Example 1 A cement calcination facility was used having the configuration shown in the flow diagram in Figure 1. The dust collection efficiencies in the cyclone dust collectors C1, K1, C2, and K2 were left unchanged at 90%, 90%, 80%, and 80%, respectively, which had been set during previous operation of the facility.

[0080] Example 1 In Comparative Example 1, the cement burning equipment was operated in the same manner as in Comparative Example 1, except that the dust collection efficiency in cyclone dust collectors C1, K1, C2, and K2 was changed to the efficiency shown in Table 1. Here, the dust collection efficiency was adjusted by adjusting the cross-sectional area of ​​the gas flow passage by increasing or decreasing the thickness of the refractory material lining the gas flow passage duct in order to adjust the flow velocity of the exhaust gas in the gas flow passage, and also by adjusting the insertion rate of the inner cylinder of the cyclone dust collector.

[0081] Comparative Example 2 The cement burning facility was operated in the same manner as in Comparative Example 1, except that the exhaust gas (calciner combustion exhaust gas) from the C-system air duct was supplied to the carbon dioxide recovery facility.

[0082] Example 2 In Comparative Example 2, the cement burning equipment was operated in the same manner as in Comparative Example 1, except that the dust collection efficiency in cyclone dust collectors C1, K1, C2, and K2 was changed to the efficiency shown in Table 1. Here, the dust collection efficiency was adjusted by adjusting the flow rate of the exhaust gas in the gas flow passage and the insertion rate of the inner cylinder of the cyclone dust collector in combination.

[0083] The ratio of the amount of carbon dioxide contained in each exhaust gas to the total amount of carbon dioxide contained in the exhaust gas discharged from the C-line air duct (calciner combustion exhaust gas) and the exhaust gas discharged from the K-line air duct in Examples 1 and 2 and Comparative Examples 1 and 2 is shown in Table 1.

[0084] [Table 1]

[0085] In Comparative Example 1, the proportion of carbon dioxide discharged from the C-line air duct was 68%, and the proportion of carbon dioxide discharged from the K-line air duct was 32%, whereas in Example 1, in which the dust collection efficiency of the lowest cyclone dust collectors C1 and K1 was reduced to 60%, and the dust collection efficiency of the cyclone dust collectors C2 and K2 one level above the lowest cyclone dust collector was increased to 90%, the proportion of carbon dioxide discharged from the C-line air duct was 81%, and the proportion of carbon dioxide discharged from the K-line air duct was 19%. In this way, it was confirmed that the amount of carbon dioxide discharged from the two air ducts can be adjusted by a very simple method of adjusting the dust collection efficiency of a specific cyclone dust collector, the lowest cyclone dust collector and the cyclone dust collector one level above the lowest cyclone dust collector, and that in Example 1, carbon dioxide in the exhaust gas (kiln combustion exhaust gas) passing through the K-line air duct can be transferred to the exhaust gas (calciner combustion exhaust gas) passing through the C-line air duct.

[0086] Comparative Example 2 is an example in which the exhaust gas (calciner combustion exhaust gas) discharged from the C-line air duct in Comparative Example 1 is supplied to a carbon dioxide recovery facility. It can be seen that this allows 68% of carbon dioxide to be recovered. Example 2 is an example in which the dust collection efficiency of the lowest cyclone dust collectors C1 and K1 in Comparative Example 2 is reduced to 60%, and the dust collection efficiency of the cyclone dust collectors C2 and K2 one level above the lowest level is increased to 90%. According to Example 2, the proportion of carbon dioxide discharged from the C-line air duct is 81%, and it was confirmed that 81% of carbon dioxide can be recovered by supplying this to a carbon dioxide recovery facility. In addition, the proportion of carbon dioxide discharged from the K-line air duct is 19%, and it was also confirmed that the amount of carbon dioxide released into the atmosphere can be suppressed while improving the amount of carbon dioxide recovered.

[0087] The production amounts of cement clinker in Comparative Examples 1 and 2 are roughly the same as the production amounts of cement clinker in Examples 1 and 2 in which the dust collection efficiency of the cyclone dust collector was adjusted. It was confirmed that the production method and burning equipment of this embodiment make it possible to adjust the amount of carbon dioxide recovered while maintaining the production amount of cement clinker, and further to improve the amount of carbon dioxide recovered, while suppressing the amount of carbon dioxide released into the atmosphere.

[0088] Furthermore, in Examples 1 and 2, although the carbon dioxide contained in the exhaust gas (kiln combustion exhaust gas) discharged from the K-system air duct was transferred to the exhaust gas passing through the C-system air duct, the total flow rate of the exhaust gas was roughly maintained at the total flow rate of the exhaust gas in Comparative Examples 1 and 2. Therefore, it was also confirmed that the required amount of cement raw materials can be dried by supplying the exhaust gas (kiln combustion exhaust gas) discharged from the K-system air duct to the drying and crushing device as a heat source for drying the cement raw materials and adjusting the operating time.

[0089] From the above results, it was confirmed that the method for producing cement clinker and the cement calcination equipment of the present embodiment can adjust the amounts of carbon dioxide contained in the two combustion exhaust gases generated in the cement calcination equipment without large-scale modification of the equipment. Furthermore, it was confirmed that by increasing the amount of carbon dioxide contained in the calciner combustion exhaust gas, it is possible to improve the amount of carbon dioxide recovered and suppress the amount of carbon dioxide emitted into the atmosphere.

Claims

1. A drying and crushing device for drying and crushing the cement raw material to produce powder raw material; a suspension preheater for preheating and calcining the powdered raw material; a rotary kiln for burning the preheated and calcined powdered raw material into cement clinker; and A method for producing cement clinker using a cement calcination facility including a cement clinker cooler for cooling the cement clinker, The suspension preheater is A calciner for calcining the powdered raw material, a C-type air duct having three or more stages of cyclone dust collectors for collecting the powder raw material and a gas flow path connecting the three or more stages of cyclone dust collectors in sequence, through which a calciner combustion exhaust gas discharged from the calciner passes; A K-system air duct has three or more stages of cyclone dust collectors that collect the powder raw material, and a gas flow path that sequentially connects the three or more stages of cyclone dust collectors, and through which kiln combustion exhaust gas discharged from the rotary kiln passes, and two different air ducts are provided; a raw material conduit K-I connecting the cyclone dust collector of the K system air duct and a gas flow path for supplying the calciner combustion exhaust gas to the cyclone dust collector of the C system air duct at the same stage as the cyclone dust collector of the K system air duct; A raw material conduit C-I that connects the cyclone dust collector of the C system air duct and a gas flow path that supplies the kiln combustion exhaust gas to the cyclone dust collector of the K system air duct that is one stage below the cyclone dust collector of the C system air duct; A raw material conduit K-II connecting the lowest cyclone dust collector of the K system air duct and the calciner; A raw material conduit C-II connecting the lowest cyclone dust collector of the C system air duct and the rotary kiln; a powder raw material supplying device that supplies the powder raw material to a topmost cyclone dust collector of at least one of the two air passages; At least one of the cyclone dust collectors at the lowest stage in the two air ducts and at least one of the cyclone dust collectors one stage above the lowest stage have a means for adjusting the dust collection efficiency of the powder raw material, The dust collection efficiency of the cyclone dust collector is adjusted by the adjustment means. A method for producing cement clinker.

2. 2. The method for producing cement clinker according to claim 1, wherein the dust collection efficiency of the lowest cyclone dust collector is reduced by the adjustment means.

3. 2. The method for producing cement clinker according to claim 1, wherein the dust collection efficiency of the cyclone dust collector one stage above the lowest stage is increased by the adjustment means.

4. 2. The method for producing cement clinker according to claim 1, wherein the temperature of the kiln combustion exhaust gas after passing through the cyclone dust collector one stage above the lowest stage in the K system air duct is 700°C or lower.

5. 2. The method for producing cement clinker according to claim 1, wherein carbon dioxide is recovered from the calciner flue gas using a carbon dioxide recovery facility.

6. 2. The method for producing cement clinker according to claim 1, wherein at least the kiln combustion exhaust gas is used for drying the cement raw materials.

7. The drying and grinding device includes a drying device or a drying and grinding device, The method for producing cement clinker according to claim 1 , wherein at least the kiln combustion exhaust gas is supplied to the drying equipment or the drying and grinding equipment.

8. A drying and crushing device for drying and crushing the cement raw material to produce powder raw material; a suspension preheater for preheating and calcining the powdered raw material; a rotary kiln for burning the preheated and calcined powdered raw material into cement clinker; and A cement burning facility including a cement clinker cooler for cooling the cement clinker, The suspension preheater is A calciner for calcining the powdered raw material, a C-type air duct having three or more stages of cyclone dust collectors for collecting the powder raw material and a gas flow path connecting the three or more stages of cyclone dust collectors in sequence, through which a calciner combustion exhaust gas discharged from the calciner passes; A K-system air duct has three or more stages of cyclone dust collectors that collect the powder raw material, and a gas flow path that sequentially connects the three or more stages of cyclone dust collectors, and through which kiln combustion exhaust gas discharged from the rotary kiln passes, and two different air ducts are provided; a raw material conduit K-I connecting the cyclone dust collector of the K system air duct and a gas flow path for supplying the calciner combustion exhaust gas to the cyclone dust collector of the C system air duct at the same stage as the cyclone dust collector of the K system air duct; A raw material conduit C-I that connects the cyclone dust collector of the C system air duct and a gas flow path that supplies the kiln combustion exhaust gas to the cyclone dust collector of the K system air duct that is one stage below the cyclone dust collector of the C system air duct; A raw material conduit K-II connecting the lowest cyclone dust collector of the K system air duct and the calciner; A raw material conduit C-II connecting the lowest cyclone dust collector of the C system air duct and the rotary kiln; a powder raw material supplying device that supplies the powder raw material to a topmost cyclone dust collector of at least one of the two air passages; At least one of the cyclone dust collectors at the lowest stage in the two air passages and at least one of the cyclone dust collectors one stage above the lowest stage have a means for adjusting the dust collection efficiency of the powder raw material. Cement baking equipment.

9. 9. The cement calcination facility of claim 8, further comprising a carbon dioxide capture system for capturing carbon dioxide from the calciner flue gas.

10. The drying and grinding device includes a drying device or a drying and grinding device, The cement burning facility according to claim 8, further comprising an exhaust gas supply pipe for supplying at least the kiln combustion exhaust gas to the drying equipment or the drying and crushing equipment.

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