Cement clinker manufacturing system and cement clinker manufacturing method

Abstract

To provide a method for producing a cement clinker, capable of: efficiently obtaining gas containing a high concentration of carbon dioxide gas when producing cement clinker; reducing an exhaust gas emission; and recovering sulfur contained in a cement clinker material.SOLUTION: A system 1 for producing a cement clinker includes: a cyclone preheater 2; a rotary kiln 3; a calcination furnace 4; a preheated material supply line 7; a clinker cooler 5; and a kiln exhaust gas discharge line 6, wherein the system further includes: a combustion-aiding gas feeder 8; a combustion-aiding gas feed channel 9; a cyclone 10, directly connected to the calcination furnace 4, for separating a cement clinker material discharged from the furnace 4 from a calcination furnace exhaust gas; a temperature-measuring device 11 for measuring temperature in the cyclone; a calcination furnace-regulating device 12 for adjusting a heating condition; a decarboxylation material-feeding channel 13; a calcination furnace exhaust gas-discharging channel 14; a heat-exchanging device 15; and a sulfur-collecting device 16 for collecting sulfur-containing material from calcination furnace exhaust gas.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a cement clinker production system and a cement clinker production method. [Background technology]

[0002] In recent years, reducing carbon dioxide emissions has become an important issue in order to curb global warming. Meanwhile, the cement industry is one of the industries that emits large amounts of carbon dioxide. Of the total amount of carbon dioxide (gaseous carbon dioxide) emitted during the production of cement, approximately 60% is emitted by the decarbonation of limestone, which is used as a raw material for cement, and approximately 40% is emitted by the combustion of fuel used during production. Methods for reducing carbon dioxide gas generated by fuel combustion include improving energy efficiency, using biomass fuel as fuel, etc. For example, Patent Document 1 describes a cement calcination apparatus that can reduce the amount of carbon dioxide gas generated by fuel combustion, which is characterized by having a main burner that injects combustible gas as the main fuel and combustible waste as the auxiliary fuel into a cement kiln.

[0003] On the other hand, it is difficult to use calcium-containing raw materials that generate less carbon dioxide as a cement raw material instead of limestone, which generates a lot of carbon dioxide, so it is difficult to reduce the amount of carbon dioxide generated by decarbonation of limestone. Known methods for reducing carbon dioxide emissions include separating and recovering the generated carbon dioxide gas, and then storing, isolating, or effectively utilizing the gas. As a method for separating and recovering generated carbon dioxide gas, for example, Patent Document 2 describes a method for separating and recovering carbon dioxide from by-product gas generated in a steelworks by a chemical absorption method, in which carbon dioxide is absorbed from the gas by a chemical absorption liquid, and then the chemical absorption liquid is heated to separate the carbon dioxide, and the carbon dioxide separation and recovery method is characterized by utilizing or making use of low-grade exhaust heat of 500°C or less generated in the steelworks. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-52746 [Patent Document 2] Japanese Patent Application Laid-Open No. 2004-292298 Summary of the Invention [Problem to be solved by the invention]

[0005] The exhaust gas generated during the production of cement clinker contains large amounts of nitrogen, oxygen, and other elements in addition to carbon dioxide. Therefore, in order to separate and recover carbon dioxide from the exhaust gas, it is necessary to use a chemical absorption method using an amine compound, for example. If the concentration of carbon dioxide contained in the exhaust gas can be increased, separation and recovery of carbon dioxide becomes easier. Furthermore, by reducing the amount of nitrogen and other substances contained in the exhaust gas, the volume of the generated exhaust gas can be relatively reduced, and the equipment for separating and recovering carbon dioxide can be made smaller. In addition, sulfur (S), which is contained in cement clinker raw materials such as waste concrete, municipal waste incineration ash, coal ash, construction soil, and iron raw materials, as well as fossil fuels such as coal and heavy oil, and waste-derived fuels such as RDF (Refuse Derived Fuel) and waste plastics, circulates and concentrates in the kiln and preheater, causing blockages in the kiln and preheater. The present invention The purpose is A cement clinker that can recover sulfur contained in cement clinker raw materials and fuels (hereinafter also referred to as "cement clinker raw materials and fuels") and prevent blockages in the kiln and preheater caused by sulfur. Manufacturing method The purpose is to provide [Means for solving the problem]

[0006] The present inventors have conducted extensive research to solve the above problems, and have come up with a cement clinker production system including a cyclone-type preheating device, a rotary kiln, a calciner, a preheated raw material supply path for supplying preheated cement clinker raw materials to the calciner, a clinker cooler, and a kiln exhaust gas discharge path, the system including a combustion-sustaining gas supply device for supplying a combustion-sustaining gas, a combustion-sustaining gas supply path for guiding the combustion-sustaining gas into the calciner, a cyclone directly connected to the calciner for separating the cement clinker raw materials discharged from the calciner from the calciner exhaust gas, and a clinker cooler. The inventors have found that the above-mentioned objects can be achieved by a cement clinker production system including a temperature measuring device for measuring the temperature inside a cyclone, a calciner adjusting device for adjusting the heating conditions of the cement clinker raw materials in the calciner, a decarbonated raw material supply path for supplying the cement clinker raw materials from the cyclone, a calciner exhaust gas discharge path for discharging the calciner exhaust gas from the cyclone, a heat exchanger for exchanging heat between the calciner exhaust gas and a combustion-supporting gas, and a sulfur recovery device for recovering sulfur-containing materials from the calciner exhaust gas, and have completed the present invention. That is, the present invention provides the following [1] to

[11] .

[0007] [1] A cyclone-type preheating device for preheating cement clinker raw materials, a rotary kiln for burning the cement clinker raw materials preheated by the cyclone-type preheating device to obtain cement clinker, a calciner including heating means disposed upstream of the rotary kiln together with the cyclone-type preheating device, and for heating the cement clinker raw materials using the heating means to promote decarbonation of the cement clinker raw materials, and a calciner for transferring the preheated cement clinker raw materials from the cyclone-type preheating device to the calciner. a clinker cooler disposed downstream of the rotary kiln for cooling the cement clinker; and a kiln exhaust gas discharge path for discharging the kiln exhaust gas generated in the rotary kiln after passing through the cyclone type preheating device, the system comprising: a combustion supporting gas supply device for supplying a combustion supporting gas having a higher oxygen concentration than air; a combustion supporting gas supply path for guiding the combustion supporting gas from the combustion supporting gas supply device into the calciner; a cyclone directly connected to the calciner for separating the cement clinker raw material discharged from the calciner from the calciner exhaust gas; a temperature measuring device for measuring the temperature inside the cyclone; a calciner adjusting device for adjusting the heating conditions of the cement clinker raw material in the calciner based on the temperature measured by the temperature measuring device; a decarbonated raw material supply path for supplying the cement clinker raw material separated from the cyclone to either or both of the cyclone type preheating device and the rotary kiln; a calciner exhaust gas discharge passage (limited to being different from the kiln exhaust gas discharge passage) for discharging the calciner exhaust gas separated from the cyclone; a heat exchanger for exchanging heat between the calciner exhaust gas flowing through the calciner exhaust gas discharge passage and the combustion-supporting gas flowing through the combustion-supporting gas supply passage; and a sulfur recovery device disposed in the calciner exhaust gas discharge passage and downstream of the heat exchanger for recovering sulfur-containing materials from the calciner exhaust gas.

[0008] [2] The cement clinker production system according to [1] above, wherein the sulfur recovery device is a dry desulfurization device including a desulfurization agent supply means for supplying a desulfurization agent to the calciner exhaust gas, and a sulfur-containing material recovery means for recovering the sulfur-containing material, which is a reaction product of the sulfur compounds in the calciner exhaust gas and the desulfurization agent, from the calciner exhaust gas. [3] The cement clinker production system according to [2], further comprising: a sulfur-containing material water-washing device for washing the sulfur-containing material recovered by the sulfur recovery device; a sulfur-containing material supply line for supplying the sulfur-containing material from the sulfur recovery device to the sulfur-containing material water-washing device; a sulfur-containing material residue discharge line for discharging sulfur-containing material residue generated in the sulfur-containing material water-washing device; a first wastewater discharge line for discharging wastewater generated in the sulfur-containing material water-washing device; and a first wastewater treatment device disposed midway along the first wastewater discharge line for recovering heavy metals and solids from the wastewater. [4] The cement clinker production system according to [1], wherein the sulfur recovery device is a wet desulfurization device including a slurry preparation means for contacting the calciner exhaust gas with a liquid material to obtain a sulfur-containing slurry, and a solid-liquid separation means for separating the sulfur-containing slurry into a solid and a liquid material containing the sulfur-containing material.

[0009] [5] The cement clinker production system according to any one of [1] to [4], further comprising: a dust collector disposed in the calciner exhaust gas discharge path and between the heat exchanger and the sulfur recovery device, for recovering quicklime-containing raw materials from the calciner exhaust gas. [6] The cement clinker production system according to [5], further comprising: a quicklime-containing raw material water-washing device for washing the quicklime-containing raw material collected by the dust collector; a quicklime-containing raw material supply line for supplying the quicklime-containing raw material from the dust collector to the quicklime-containing raw material water-washing device; a quicklime-containing raw material residue discharge line for discharging quicklime-containing raw material residue generated in the quicklime-containing raw material water-washing device; a second wastewater discharge line for discharging wastewater generated in the quicklime-containing raw material water-washing device; and a second wastewater treatment device disposed in the second wastewater discharge line for recovering heavy metals and solids from the wastewater. [7] The cement clinker production system according to any one of [1] to [6], further comprising a confluence passage for confluence of a portion of the calciner exhaust gas flowing through the calciner exhaust gas discharge passage with the combustion-supporting gas flowing through the combustion-supporting gas supply passage. [8] The cement clinker production system according to any one of [1] to [7], further comprising a chlorine bypass device for extracting and cooling a portion of the exhaust gas generated in the rotary kiln without passing through the cyclone preheating device, removing solids, discharging the exhaust gas from which the solids have been removed, and classifying the solids into coarse powder and fine powder, using the coarse powder as part of the cement clinker raw material, and recovering the fine powder. [9] The cement clinker production system according to any one of [1] to [8], further comprising an oxygen concentration measuring device for measuring the oxygen concentration in the cyclone, and the calciner adjustment device adjusts the heating conditions of the cement clinker raw materials in the calciner based on the temperature measured by the temperature measuring device and the oxygen concentration measured by the oxygen concentration measuring device.

[0010]

[10] A method for producing cement clinker using the cement clinker production system according to any one of [1] to [9], wherein heating conditions for the cement clinker raw materials in the calciner are adjusted so that the temperature of the cement clinker raw materials in the calciner is 950°C or higher, and the temperature in the cyclone is 880°C or higher and the oxygen concentration is 3.0% by volume or lower.

[11] The method for producing cement clinker according to

[10] , wherein the adjustment of the heating conditions is one or more adjustments selected from the oxygen concentration of the combustion-supporting gas, the amount of the combustion-supporting gas supplied to the heating means, and the amount of fuel supplied to the heating means. [Effects of the Invention]

[0011] Cement clinker of the present invention According to the manufacturing method ofBy recovering the sulfur contained in the cement clinker raw fuel, it is possible to prevent blockages in the kiln and preheater caused by sulfur, and it is possible to increase the amount of cement clinker raw fuel and the like derived from waste with a high sulfur content. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram schematically illustrating an example of a cement clinker production system of the present invention using a dry desulfurization device. [Figure 2] FIG. 10 is a graph showing the change in decarbonation rate when the temperature is changed in Example 7. DETAILED DESCRIPTION OF THE INVENTION

[0013] The cement clinker production system of the present invention will be described in detail below with reference to FIG. FIG. 1 is a schematic diagram showing an example of an embodiment of a cement clinker production system according to the present invention. The cement clinker production system 1 of the present invention includes a cyclone-type preheating device 2 for preheating cement clinker raw materials, a rotary kiln 3 for burning the cement clinker raw materials preheated by the cyclone-type preheating device 2 to obtain cement clinker, a calciner 4 including a heating means 4a disposed upstream of the rotary kiln 3 together with the cyclone-type preheating device 2, and for heating the cement clinker raw materials using the heating means to promote decarbonation of the cement clinker raw materials, and a calciner 5 for burning the preheated cement clinker raw materials from the cyclone-type preheating device 2. The cement clinker production system (1) includes a preheated raw material supply line (7) for supplying the preheated cement clinker raw material to the calciner, a clinker cooler (5) disposed downstream of the rotary kiln (3) for cooling the cement clinker, and a kiln exhaust gas discharge line (6) for discharging the kiln exhaust gas generated in the rotary kiln after passing through a cyclone-type preheating device (2). The system also includes a combustion-supporting gas supply device (8) for supplying a combustion-supporting gas having a higher oxygen concentration than air, and a combustion-supporting gas supplying device (8) for introducing the combustion-supporting gas from the combustion-supporting gas supply device (8) into the calciner (4). a cyclone 10 directly connected to the calciner 4 for separating the cement clinker raw material from the calciner 4 and the calciner exhaust gas; a temperature measuring device 11 for measuring the temperature inside the cyclone 10; a calciner adjusting device 12 for adjusting the heating conditions of the cement clinker raw material in the calciner 4 based on the temperature measured by the temperature measuring device 11; and a calciner adjusting device 12 for adjusting the heating conditions of the cement clinker raw material in the calciner 4 based on the temperature measured by the temperature measuring device 11. The separated cement clinker raw material is supplied from the cyclone 4 to either or both of the cyclone type preheating device 2 and the rotary kiln 3. the calciner exhaust gas supply line 9; a calciner exhaust gas discharge line 14 (which must be different from the kiln exhaust gas discharge line 6) for discharging the separated calciner exhaust gas from the cyclone 10; a heat exchanger 15 for exchanging heat between the calciner exhaust gas flowing through the calciner exhaust gas discharge line 14 and the combustion-sustaining gas flowing through the combustion-sustaining gas supply line 9; and a sulfur recovery unit 16 disposed midway along the calciner exhaust gas discharge line 14 and downstream of the heat exchanger 15 for recovering sulfur-containing materials from the calciner exhaust gas.

[0014] The cyclone preheating device 2 comprises two or more cyclone heat exchangers 2a to 2d. The multiple cyclone heat exchangers 2a to 2d are connected by a flow path for moving the cement clinker raw material and kiln exhaust gas discharge paths 6a to 6e for discharging the exhaust gas generated in the rotary kiln 3 after passing through the multiple cyclone heat exchangers 2a to 2d. The kiln exhaust gas discharge paths 6a to 6e may also serve as a flow path for moving the cement clinker raw material. The number of cyclone heat exchangers is two or more, typically four to five. The multiple cyclone heat exchangers are typically arranged vertically. The cement clinker raw materials are fed into cyclone heat exchanger 2a, which is disposed at the forefront of cyclone preheating device 2, where they are centrifuged while exchanging heat with the kiln exhaust gas, and then fed from the bottom of cyclone heat exchanger 2a into cyclone heat exchanger 2b, which is disposed downstream, and then centrifuged again while exchanging heat with the exhaust gas, before being fed into cyclone heat exchanger 2c, which is disposed downstream. In this way, the cement clinker raw materials are preheated (heated) by the exhaust gas and move sequentially through cyclone heat exchangers 2b to 2c, which are disposed downstream, before being fed into calciner 4.

[0015] By preheating the cement clinker raw material in the cyclone preheating device 2, the amount of fuel input used to promote decarbonation in the calciner 4 can be reduced. In the cyclone preheating device 2, the cement clinker raw materials are preheated to preferably 400 to 900°C, more preferably 500 to 800°C, and particularly preferably 600 to 750°C. If the temperature is 400°C or higher, the amount of fuel used to promote decarbonation in the calciner can be reduced. If the temperature is 900°C or lower, decarbonation of the cement clinker raw materials is not promoted as easily in the cyclone preheating device 2, and therefore the carbon dioxide concentration in the kiln exhaust gas can be prevented from increasing.

[0016] The cement clinker raw material is not particularly limited, and any common raw material for cement clinker can be used. Specific examples include natural raw materials such as limestone, soil, clay, silica stone, and iron raw materials, as well as waste or by-products such as coal ash, steel slag, municipal waste incineration ash, sewage sludge incineration ash, ready-mixed concrete sludge, waste concrete fine powder, construction soil, and fluidized bed fly ash (ash generated when coal, municipal waste, sewage sludge, etc. are incinerated in a fluidized bed furnace). Calcium-containing waste (described below) that has absorbed carbon dioxide may also be used as the cement clinker raw material. Furthermore, the cement clinker production system of the present invention can recover sulfur contained in cement clinker raw materials and prevent blockages in the kiln and preheater caused by sulfur, which allows for the use of more raw materials with a high sulfur content (e.g., waste concrete fines, fluidized bed fly ash, etc.) as cement clinker raw materials. The cement clinker raw materials are prepared by pulverizing and mixing various raw materials in an appropriate ratio using a raw material mill, and then the mixture is fed into the cyclone preheating device 2. The particle size of the cement clinker raw materials is preferably 100 μm or less, from the viewpoint of facilitating the production of cement clinker. Furthermore, a portion of the cement clinker raw materials (for example, contaminated soil containing a large amount of organic matter) may be directly charged into the rotary kiln 3 without being charged into the cyclone preheating device 2.

[0017] The preheated cement clinker raw material is supplied to the calciner 4 through a preheated raw material supply passage 7 connected to any one of the two or more cyclone heat exchangers 2a to 2d that make up the cyclone preheating device 2. In Fig. 1, the preheated raw material supply passage 7 is connected to the cyclone heat exchanger 2c that is disposed second or more downstream from the most downstream side of the cyclone preheating device 2, and the cement clinker raw material that has been preheated by passing through the cyclone heat exchangers 2a to 2c is fed from the cyclone heat exchanger 2c through the preheated raw material supply passage 7 into the calciner 4. By connecting the preheated raw material supply passage 7 to the cyclone heat exchanger 2c that is located second from the most downstream side, it is possible to feed sufficiently preheated cement clinker raw material into the calciner 4.

[0018] The calciner 4 is disposed upstream of the rotary kiln 3 together with the cyclone preheating device 2 for the purpose of heating the cement clinker raw materials by burning fuel using a heating means 4a to promote decarbonation of the cement clinker raw materials. Here, decarbonation of cement clinker raw materials means decomposing calcium carbonate (CaCO3), the main component of limestone contained in cement clinker raw materials, into quicklime (CaO) and carbon dioxide (CO2) by heating. When the cement clinker raw materials are heated in the calciner 4 using a combustion-supporting gas with a higher oxygen concentration than air, the carbon dioxide partial pressure increases. Therefore, a higher temperature is required to promote decarbonation, and a higher temperature is required than when air is used as the combustion-supporting gas. For this reason, heating in the calciner 4 is performed so that the temperature of the heated cement clinker raw materials is preferably 950°C or higher, more preferably 960 to 1,100°C, even more preferably 975 to 1,080°C, and particularly preferably 1,000 to 1,050°C. A temperature of 950°C or higher can further promote decarbonation of the cement clinker raw materials even in an atmosphere with a high carbon dioxide partial pressure, and can further promote volatilization of sulfur compounds contained in the cement clinker raw materials. Furthermore, even when the decarbonated cement clinker raw materials are fed directly from the calciner 4 into the rotary kiln 3 through the decarbonation raw material supply path 13, the temperature inside the rotary kiln 3 is not excessively reduced. If the temperature is 1,100°C or less, clogging due to sintering of the raw materials can be prevented. The above temperature can be adjusted as appropriate, for example, by adjusting the heating conditions of the cement clinker raw material in the calciner 4 using the calciner adjustment device 12 (described later).

[0019] The decarbonation of the cement clinker raw material is promoted in the calciner 4 by directly heating the cement clinker raw material using heating means 4a, which burns fuel with a combustion-supporting gas. An example of the heating means 4a is a burner. The fuel is fed to the heating means 4a through a fuel supply passage 4b. The fuel used in the calciner 4 is not particularly limited, and examples thereof include fossil fuels such as coal, heavy oil, and natural gas; refuse-derived fuels such as RDF (refuse-derived fuel), waste plastics, and waste oil; biomass such as coconut husks; biogas obtained by gasifying biomass; and synthetic methane produced by methanation using carbon dioxide as a raw material. These may be used alone or in combination of two or more. In particular, the cement clinker production system of the present invention makes it possible to use fuels with a high sulfur content (for example, coal, heavy oil, RDF, waste plastics, etc.). Furthermore, the use of carbon-free fuels such as biomass and synthetic methane can substantially reduce carbon dioxide emissions in cement clinker production.

[0020] The combustion-supporting gas used in the calciner 4 has a higher oxygen concentration than air. By using such a combustion-supporting gas, the carbon dioxide concentration of the calciner exhaust gas can be increased. Furthermore, by using the combustion-supporting gas, the combustibility of the fuel is improved, so that even fuels that have been difficult to use in the past because they are difficult to pulverize can be used. From the viewpoint of increasing the carbon dioxide concentration in the calciner exhaust gas, the oxygen concentration of the combustion-supporting gas is preferably 21% by volume or more, more preferably 25% by volume or more, and particularly preferably 30% by volume or more, based on 100% by volume including water vapor. Also, from the viewpoint of decreasing the oxygen concentration in cyclone 10 directly connected to calciner 4 (for example, to 2% by volume or less) and making it easier to control combustion in calciner 4, the oxygen concentration is preferably 90% by volume or less, more preferably 80% by volume or less, even more preferably 70% by volume or less, even more preferably 60% by volume or less, and particularly preferably 50% by volume or less.

[0021] The combustion-sustaining gas used in the calciner 4 is supplied from a combustion-sustaining gas supply device 8 and led to the calciner 4 through a combustion-sustaining gas supply path 9 . The combustion-supporting gas supply passage 9 may be arranged (not shown) so that the temperature of the combustion-supporting gas passing through the combustion-supporting gas supply passage 9 is indirectly heated by air heated by heat exchange with the cement clinker in the clinker cooler 5. Alternatively, the temperature of the combustion-supporting gas may be raised by the heat of the cement clinker by passing the combustion-supporting gas supply passage 9 through a part of the downstream side of the cement cooler (the outlet side of the clinker cooler) (not shown). By increasing the temperature of the combustion-supporting gas, the amount of fuel input used in the calciner 4 can be reduced.

[0022] Examples of the combustion-supporting gas supply device 8 include an oxygen tank, an air separation unit (ASU) that separates oxygen from air, and a water electrolysis device that generates oxygen by electrolysis of water. Methods for separating oxygen from air include cryogenic separation, adsorption separation, membrane separation, etc. Among these, cryogenic separation is preferred from the viewpoint of obtaining a large amount of oxygen.

[0023] The combustion-sustaining gas supplied from the combustion-sustaining gas supply device 8 has a higher oxygen concentration than air. The combustion-sustaining gas may be used in the calciner 4 as is, or its composition may be appropriately adjusted before being used in the calciner 4. For example, from the viewpoint of preventing the oxygen concentration of the combustion-supporting gas used in the calciner 4 from becoming excessively high, which would make it difficult to control combustion, increasing the carbon dioxide concentration of the calciner exhaust gas, and reducing the amount of oxygen remaining in the calciner exhaust gas, the combustion-supporting gas supplied from the combustion-supporting gas supply device 8 may be mixed with carbon dioxide gas, and the resulting mixed gas may be used as the combustion-supporting gas used in the calciner 4. As the carbon dioxide gas, carbon dioxide gas flowing through the furnace exhaust gas supply passage 14 or contained in the furnace exhaust gas may be used (described later).

[0024] Furthermore, in order to lower the temperature required to promote decarbonation by lowering the carbon dioxide partial pressure, the combustion-supporting gas supplied from the combustion-supporting gas supply device 8 may be mixed with water vapor, and the resulting mixed gas may be used as the combustion-supporting gas in the calciner 4. The carbon dioxide concentration of the mixed gas (a mixture of the combustion-supporting gas supplied from the combustion-supporting gas supply device 8 and at least one of carbon dioxide gas and water vapor) is preferably 10 to 79 volume %, more preferably 20 to 75 volume %, and even more preferably 30 to 70 volume %, relative to 100 volume % including water vapor. Furthermore, from the viewpoint of reducing the volume of the exhaust gas generated in the calciner 4 and increasing the carbon dioxide concentration of the exhaust gas, it is preferable that the combustion-supporting gas used in the calciner 4 does not contain gases other than oxygen, carbon dioxide, and water vapor (for example, nitrogen). The concentration of gases other than oxygen, carbon dioxide, and water vapor in the combustion-supporting gas is preferably 10% by volume or less, more preferably 5% by volume or less, and particularly preferably 2% by volume or less, based on 100% by volume including water vapor. In addition, the composition of the combustion-supporting gas may be adjusted appropriately based on either or both of the temperature measured using a temperature measuring device 11 (described later) and the oxygen concentration measured using an oxygen concentration measuring device 30 (described later).

[0025] The cement clinker raw material (hereinafter also referred to as "decarbonated raw material") that has been heated in the calciner 4 and whose decarbonation has been promoted is discharged, while maintaining the high temperature after heating, into a cyclone 10 that is directly connected to the calciner 4 and that separates the cement clinker raw material and calciner exhaust gas discharged from the calciner 4. In the cyclone 10, the raw material for decarbonation discharged from the calciner 4 and the calciner exhaust gas are separated by centrifugation or the like. The separated raw material for decarbonation is supplied to either or both of the cyclone preheating device 2 and the rotary kiln 3 through a raw material for decarbonation supply path 13 while maintaining the high temperature after heating. When the raw material for decarbonation is supplied to the cyclone preheating device 2, it is usually supplied to a cyclone heat exchanger 2d disposed on the most downstream side of the cyclone preheating device 2. The separated calciner exhaust gas (exhaust gas containing carbon dioxide gas) is discharged through a calciner exhaust gas discharge passage 14 (which must be different from the kiln exhaust gas discharge passage 6).

[0026] The temperature inside the cyclone 10 is preferably 880°C or higher, more preferably 900 to 1,050°C, even more preferably 925 to 1,020°C, and particularly preferably 950 to 1,000°C. If the temperature is 880°C or higher, quicklime produced in association with the decarbonation of the cement clinker raw material is less likely to be recarbonated in the cyclone 10, thereby making it possible to further reduce the amounts of calcium carbonate, gypsum, and the like produced by the recarbonation of quicklime. Furthermore, components such as sulfur volatilized in the calciner 4 are less likely to be adsorbed onto the cement clinker raw material. This allows sulfur compounds (e.g., SOx) and carbon dioxide to be efficiently separated from the decarbonated raw material in the cyclone 10. The oxygen concentration in the cyclone 10 is preferably 3.0% by volume or less, more preferably 2.5% by volume or less, even more preferably 1.0% by volume or less, and particularly preferably 0.5% by volume or less. If the oxygen concentration is 3.0% by volume or less, sulfur in the cement clinker raw material can be efficiently volatilized in the calciner 4. The temperature and oxygen concentration can be adjusted as appropriate, for example, by adjusting the heating conditions for the cement clinker raw material in the calciner 4 using the calciner adjustment device 12 (described later).

[0027] The calciner adjusting device 12 is a device for adjusting the heating conditions of the cement clinker raw material in the calciner 4 based on the temperature measured by the temperature measuring device 11. Furthermore, the calciner adjusting device 12 may adjust the heating conditions based on the oxygen concentration measured by the oxygen concentration measuring device 30 in addition to the temperature. The above temperature or oxygen concentration may be the temperature or oxygen concentration near the inlet of cyclone 10 directly connected to calciner 4 (the position where cement clinker raw materials and the like enter cyclone 10 from calciner 4), or may be the temperature near the outlet of cyclone 10 for calciner exhaust gas (the position where calciner exhaust gas leaves cyclone 10 into calciner discharge channel 14). The temperature measuring device 11 or the oxygen concentration measuring device 30 may be arranged as appropriate in the region from the connection between the cyclone 10 and the calciner 4 to the connection between the cyclone 10 and the calciner exhaust gas discharge passage 14, for example, as long as it can measure the temperature or oxygen concentration inside the cyclone 10. The calciner adjusting device 12 may be any device capable of adjusting the heating conditions of the cement clinker raw material in the calciner 4, and may be disposed at a location remote from the calciner 4, for example, online.

[0028] By adjusting the heating conditions of the cement clinker raw material in the calciner 4, for example, the temperature of the cement clinker raw material in the calciner 4 can be adjusted to 950°C or higher, and the temperature inside the cyclone 10 can be adjusted to 880°C or higher and the oxygen concentration can be adjusted to 3.0% by volume or lower. Examples of methods for adjusting the heating conditions include methods for adjusting one or more of the composition of the combustion-supporting gas (e.g., oxygen concentration), the temperature and supply amount of the combustion-supporting gas to the heating means 4a, and the type and supply amount of fuel supplied to the heating means 4a.

[0029] A heat exchanger 15 is disposed between the calciner exhaust gas discharge path 14 and the combustion-supporting gas supply path 9, for exchanging heat between the calciner exhaust gas flowing through the calciner exhaust gas discharge path 14 and the combustion-supporting gas flowing through the combustion-supporting gas supply path 9. The heat exchanger 15 is not particularly limited, but a device in which the calciner exhaust gas and the combustion-supporting gas do not mix is ​​preferred. For example, a device in which the combustion-supporting gas supply path 9 and the calciner exhaust gas discharge path 14 are disposed so that the temperature of the combustion-supporting gas flowing through the combustion-supporting gas supply path 9 is indirectly heated by air flowing through the calciner exhaust gas discharge path 14 and heated by heat exchange with the calciner exhaust gas is raised.

[0030] By providing the heat exchanger 15, the combustion-supporting gas flowing through the combustion-supporting gas supply passage 9 is indirectly heated and raised in temperature, thereby making it possible to reduce the amount of fuel used in the calciner 4. The temperature of the heated combustion-supporting gas is preferably 600 to 800°C, more preferably 650 to 750°C. If the temperature is 600°C or higher, the amount of fuel used in the calciner 4 can be further reduced. However, it may be difficult to raise the temperature above 800°C using calciner exhaust gas. Furthermore, by indirectly cooling and lowering the temperature of the calciner exhaust gas (exhaust gas containing carbon dioxide) flowing through the calciner exhaust gas discharge path 14, it is possible to improve the efficiency of recovering quicklime-containing raw materials (fine powder containing quicklime) from the calciner exhaust gas in the dust collector 22 (described later) and the efficiency of recovering sulfur-containing materials from the calciner exhaust gas in the sulfur recovery device 16 (described later). The temperature of the cooled calciner exhaust gas is preferably 150°C (acid dew point) to 400°C, more preferably 180 to 300°C. If the temperature is 400°C or lower, the chlorine (originating from cement clinker raw materials and waste plastics used as a fuel substitute in the calciner) and sulfur contained in the calciner exhaust gas can be precipitated as alkali chlorides, alkali sulfates, calcium chloride, gypsum, and the like. Furthermore, a general-purpose dust collector can be used, for example, for the filter cloth of the bag filter used as the dust collector. If a combustion-supporting gas is used to lower the temperature below 150°C (acid dew point), sulfuric acid gas and hydrochloric acid gas in the calciner exhaust gas condense to produce sulfuric acid and hydrochloric acid, which may corrode the equipment.

[0031] In addition to the heat exchanger 15, a calciner exhaust gas temperature reducing device (not shown) for reducing the temperature of the calciner exhaust gas flowing through the calciner exhaust gas discharge path 14 may be provided in the calciner exhaust gas discharge path 14, upstream of the sulfur recovery device 16. The calciner exhaust gas temperature reducing device is not particularly limited as long as it can reduce the temperature of the calciner exhaust gas. For example, a device for exchanging heat between a liquid and a carbon dioxide-containing exhaust gas may be used.

[0032] A sulfur recovery device 16 is disposed in the calciner exhaust gas discharge path 14 and downstream of the heat exchanger 15 (downstream of the position where the heat exchanger 15 is disposed in the calciner exhaust gas discharge path 14) for recovering sulfur-containing substances from the calciner exhaust gas flowing through the calciner exhaust gas discharge path 14. Examples of the sulfur recovery unit 16 include (i) a dry desulfurization unit, (ii) a wet desulfurization unit, etc. These will be described in detail below.

[0033] (i) Dry desulfurization equipment An example of a dry desulfurization apparatus includes a desulfurization agent supply means for supplying a desulfurization agent to the calciner exhaust gas, and a sulfur-containing material recovery means for recovering, from the calciner exhaust gas, sulfur-containing materials that are reaction products of the desulfurization agent and the sulfur compounds in the calciner exhaust gas. The desulfurizing agent is supplied to the calciner exhaust gas using a desulfurizing agent supplying means such as a sprayer, etc. Examples of the desulfurizing agent include calcium-based desulfurizing agents and sodium-based desulfurizing agents. Examples of calcium-based desulfurizing agents include hydrated lime (Ca(OH)2), quicklime (CaO), and calcium carbonate (CaCO3). These may be used alone or in combination of two or more. Examples of sodium-based desulfurizing agents include sodium bicarbonate (NaHCO3), sodium hydroxide (NaOH), and sodium carbonate (Na2CO3). These may be used alone or in combination of two or more.

[0034] When a calcium-based desulfurizing agent is used as the desulfurizing agent, the sulfur-containing material, which is a reaction product of the desulfurizing agent and the sulfur compounds in the calciner exhaust gas, contains gypsum (CaSO4). Therefore, the sulfur-containing material (containing gypsum) recovered by the sulfur-containing material recovery means may be added to cement in the finishing step of cement production. Furthermore, if the cement clinker raw material contains a large amount of chlorine or if a dust collector 22 (described later) is not used, the sulfur compounds may contain a large amount of chlorine and alkali metals (sodium, potassium). In such cases, a sulfur-containing material washing device 17 may be provided to wash the sulfur-containing material recovered in the sulfur recovery device 16. The sulfur-containing material recovered in the sulfur recovery unit 16 is supplied to a sulfur-containing material washing unit 17 through a sulfur-containing material supply line 18. In the sulfur-containing material washing unit 17, the sulfur-containing material is washed with water, thereby removing chlorine (present in the form of alkali chlorides such as CaCl2 and KCl) contained in the sulfur-containing material.

[0035] In the sulfur-containing material washing device 17, the sulfur-containing material residue (resulting from washing the sulfur-containing material with water) generated after washing with water is discharged to the outside through a sulfur-containing material residue discharge path 19. In the sulfur-containing material washing device 17, wastewater generated after washing is discharged to the outside through a first wastewater discharge channel 20. A first wastewater treatment device 21 for recovering heavy metals and solids from the wastewater may be provided in the first wastewater discharge channel 20 .

[0036] When a sodium-based desulfurization agent is used as the desulfurization agent, since most sulfur-containing substances are water-soluble, the sulfur-containing substances are dissolved in water, and then solids and heavy metals are recovered from the aqueous solution in which the sulfur-containing substances are dissolved, and the aqueous solution is then discharged to the outside.

[0037] (ii) Wet desulfurization equipment Examples of wet desulfurization devices include those including a slurry preparation means for contacting the calciner exhaust gas with a liquid material to obtain a sulfur-containing slurry, and a solid-liquid separation means for separating the sulfur-containing slurry into a solid and a liquid material containing the sulfur-containing material. Examples of a method for contacting the calciner exhaust gas with a liquid include a method in which the liquid is sprayed into the calciner exhaust gas. Examples of the liquid include water, etc. The liquid may contain slaked lime (Ca(OH)2), quicklime (CaO), calcium carbonate (CaCO3), etc., from the viewpoint of facilitating the absorption of sulfur compounds in the calciner exhaust gas and enabling the production of sulfur-containing materials including gypsum, etc. The pH of the liquid is preferably 7 or higher, more preferably 7 to 9. If the pH is 7 or higher, sulfur compounds in the calciner exhaust gas are more likely to be absorbed by the liquid. In order to adjust the pH to 7 or higher, the liquid may contain sodium hydroxide, potassium hydroxide, or the like. An example of the slurry preparation means is a scrubber.

[0038] The sulfur-containing slurry obtained by contacting the calciner exhaust gas with the liquid material is separated into a solid material containing the sulfur-containing material and a liquid material using a solid-liquid separation means. Examples of the solid-liquid separation means include a filter press, a centrifuge, and a belt filter. The separated sulfur-containing material contains gypsum (CaSO4). Therefore, the sulfur-containing material (containing gypsum) recovered by the solid-liquid separation means may be added to cement in the finishing step of cement production. If the liquid contains only a small amount of chloride ions and sulfate ions, the liquid may be reused as the liquid for contacting the calciner exhaust gas.

[0039] A dust collector 22 for recovering quicklime-containing raw materials (fine powder containing quicklime) from the calciner exhaust gas may be disposed in the calciner exhaust gas discharge path 14, between the heat exchanger 15 and the sulfur recovery unit 16. The quicklime-containing raw materials contain, in addition to quicklime, precipitated sulfates such as CaSO4 and K2SO4, alkali chlorides such as CaCl2 and KCl, and the like. Examples of the dust collector 22 include a cyclone, a bag filter, and an electrostatic precipitator. By providing the dust collector 22, the amount of desulfurization agent used in the sulfur recovery unit 16 can be reduced. In addition, excessive load on the sulfur recovery unit can be prevented.

[0040] The quicklime-containing raw material collected by the dust collector 22 is supplied to a quicklime-containing raw material water washing device 23 through a quicklime-containing raw material supply path 24 . In the quicklime-containing raw material washing device 23, the quicklime-containing raw material is washed with water, thereby removing chlorine (present in the form of alkali chlorides such as CaCl2 and KCl) contained in the quicklime-containing material. In quicklime-containing raw material water washing device 23, the quicklime-containing raw material residue generated after washing is discharged to the outside through quicklime-containing residue discharge path 25. The residue generated after washing contains hydrated lime (Ca(OH)2) and gypsum (CaSO4), which may be added to cement in the finishing process of cement production.

[0041] In the quicklime-containing raw material washing device 23, wastewater generated after washing is discharged to the outside through a second wastewater discharge channel 26. A second wastewater treatment device 27 for recovering heavy metals and solids from the wastewater may be provided in the second wastewater discharge channel 26 .

[0042] For the purpose of adjusting the composition of the combustion-supporting gas, a confluence passage 28 may be provided for confluence of a portion of the calciner exhaust gas flowing through the calciner exhaust gas supply passage 14 with the combustion-supporting gas flowing through the combustion-supporting gas supply passage 9. By circulating a portion of the calciner exhaust gas as part of the combustion-supporting gas, it is possible to reduce the amount of exhaust gas that is ultimately discharged to the outside through the calciner exhaust gas discharge path 14. The amount of carbon dioxide-containing exhaust gas circulating through the calciner exhaust gas discharge path 14 and used as part of the combustion-supporting gas is preferably 50 to 70% by volume. The confluence passage 28 is preferably connected to the calciner exhaust gas discharge passage 14 at a position midway along the calciner exhaust gas discharge passage 14 and downstream of the sulfur recovery device 16 . By connecting in this manner, the calciner exhaust gas that is merged from the calciner exhaust gas supply line 14 with the combustion-supporting gas flowing through the combustion-supporting gas supply line 9 is the gas from which quicklime-containing dust (quicklime-containing raw material) and the like have been collected in the dust collector 22 and the sulfur recovery unit 16. This reduces the accumulation and adhesion of the dust in the calciner 4, which has an adverse effect on fuel combustion, and the adverse effect on heat exchange between the carbon dioxide-containing exhaust gas and the combustion-supporting gas due to the accumulation and adhesion of the dust in the calciner exhaust gas discharge line 14.

[0043] The calciner exhaust gas from which the quicklime-containing raw material and sulfur-containing material have been recovered in the dust collector 22 and sulfur recovery unit 16 has a high concentration of carbon dioxide gas. The calciner exhaust gas discharge path 14 is different from the kiln exhaust gas discharge paths 6a to 6e, which are used to discharge exhaust gas generated in the rotary kiln 3. By completely separating the calciner exhaust gas discharge path 14 from the kiln exhaust gas discharge paths 6a to 6e, it is possible to recover only the calciner exhaust gas with a high concentration of carbon dioxide.

[0044] Since the calciner exhaust gas has a high carbon dioxide concentration, it is easy to separate and recover the carbon dioxide from the calciner exhaust gas. The carbon dioxide concentration of the calciner exhaust gas is preferably 80% by volume or more, more preferably 85% by volume or more, and particularly preferably 90% by volume or more, based on 100% by volume excluding water vapor. The carbon dioxide concentration can be increased by adjusting the oxygen concentration of the combustion-supporting gas. Specifically, the carbon dioxide concentration can be increased by increasing the oxygen concentration of the combustion-supporting gas or decreasing the concentrations of gases other than oxygen, carbon dioxide, and water vapor (e.g., nitrogen) in the combustion-supporting gas. The temperature of the calciner exhaust gas discharged from the calciner 4 is usually 950 to 1,100° C. Since the calciner exhaust gas is at a high temperature, the calciner exhaust gas may be used to heat water to generate steam, which may then be used to generate power using a steam turbine.

[0045] Carbon dioxide gas may be purified by removing oxygen, nitrogen, water vapor, etc. from the calciner exhaust gas. When the concentration of carbon dioxide gas in the calciner exhaust gas is high, the carbon dioxide gas can be purified by directly compressing and cooling it to liquefy it, without using a chemical absorbent such as an amine to separate and recover the carbon dioxide gas.

[0046] Cement clinker can be obtained by burning the cement clinker raw materials in the rotary kiln 3. The burning temperature of the cement clinker raw materials may be a general temperature used in cement clinker production, and is usually 1,400°C or higher. In the rotary kiln 3, the fuel used to burn the raw materials for cement clinker can be the same as the fuel used in the calciner 4. In addition, fuels that are difficult to crush, such as contaminated soil containing a large amount of organic components or waste tires, can be directly charged into the rotary kiln 3 through the raw material charging port.

[0047] The exhaust gas generated in the rotary kiln 3 flows through kiln exhaust gas discharge paths 6a to 6e, which are used to discharge the exhaust gas after passing through the cyclone preheating device 2, and is then discharged from the top of the cyclone preheating device 2. After dust is removed using a cyclone, a bag filter, an electrostatic precipitator, or the like, the exhaust gas is discharged to the outside through a chimney. Here, carbon dioxide gas may be separated and recovered from the kiln exhaust gas. Examples of methods for separating and recovering carbon dioxide gas from the kiln exhaust gas include a chemical absorption method using monoethanolamine or the like as a carbon dioxide absorbent, a solid adsorption method, and a membrane separation method. Alternatively, a portion of the kiln exhaust gas may be extracted and cooled without passing through the cyclone preheating device 2, and after the solids have been removed, the exhaust gas from which the solids have been removed may be discharged. At the same time, the solids may be classified into coarse and fine powders, and the coarse powder may be used as part of the cement clinker raw material. A chlorine bypass device 29 may be provided to recover the fine powder. It should be noted that "coarse powder" tends to have a high content of cement clinker raw material components and a low content of chlorine, while "fine powder" tends to have a high content of chlorine. The chlorine bypass unit 29 is usually installed at the connection between the cyclone preheater 2 and the rotary kiln 3. By installing the chlorine bypass unit 29, it is possible to use a larger amount of chlorine-containing waste, such as municipal waste incineration ash, as a cement clinker raw material or fuel for the rotary kiln. The kiln exhaust gas discharged from the chlorine bypass device 29 is usually returned to the kiln exhaust gas discharge path 6a.

[0048] The cement clinker obtained in the rotary kiln 3 is fed into a clinker cooler 5, which is disposed downstream of the rotary kiln 3, for cooling the cement clinker, and is cooled there. In order to perform heating in the calciner 4 and the rotary kiln 3 more efficiently, the air used to cool the cement clinker may be divided into an upstream side and a downstream side of the clinker cooler 5, and the downstream side air after cooling the cement clinker may be used to indirectly heat the combustion-supporting gas passing through the combustion-supporting gas supply path 9. Also, different gases may be used for cooling the upstream side and the downstream side. Specifically, air may be used as the gas for cooling the upstream side of the clinker cooler 5, and the combustion-supporting gas passing through the combustion-supporting gas supply passage 9 may be used as the gas for cooling the downstream side. The gas that cools the upstream side exchanges heat with high-temperature cement clinker, and is then used as a combustion-supporting gas for burning fuel in the rotary kiln 3. Note that the gas that cools the upstream side exchanges heat at the inlet side of the clinker cooler 5, and therefore becomes hotter after heat exchange than the gas that cools the downstream side.

[0049] Electric energy may also be used to heat the air and combustion-supporting gas used when burning fuel in the rotary kiln 3, and to assist in heating the rotary kiln 3 and the calciner 4. Examples of heating methods using electric energy include plasma heating, resistance heating, and microwave heating. If renewable energy is used as the electric energy, carbon dioxide emissions can be further reduced.

[0050] In the method for producing cement clinker using the cement clinker production system 1 described above, the calciner exhaust gas generated in the calciner 4 may be recovered and the carbon dioxide gas in the exhaust gas may be used. One example of the use of carbon dioxide is methanation, which is the reaction of hydrogen and carbon dioxide to produce methane (synthetic methane) and water. Specifically, there is a method of producing methane from hydrogen gas and carbon dioxide gas contained in the exhaust gas using a catalyst. Hydrogen gas can be obtained by electrolyzing water, etc. If the electrical energy used for electrolyzing water is derived from renewable energy sources such as hydraulic power, wind power, geothermal power, or solar power, carbon dioxide emissions can be further reduced. In this process, oxygen is also produced, and this oxygen may be used as the oxygen contained in the combustion-supporting gas described above.

[0051] Examples of the catalyst include Rh / Mn-based, Rh-based, Ni-based, Pd-based, and Pt-based catalysts. A carrier may also be used to support the catalyst. Examples of the carrier include CeO2, ZrO2, Y2O3, Al2O3, MgO, and TiO2. These may be selected appropriately. From the viewpoint of further reducing carbon dioxide emissions, the produced methane can be used as fuel for at least one of the rotary kiln 3 and the calciner 4. The produced methane may also be used separately as fuel for power generation.

[0052] Another example of the use of carbon dioxide gas is the carbonation of calcium-containing waste. Specifically, this method involves bringing the exhaust gas into contact with calcium-containing waste, and allowing the calcium-containing waste to absorb the carbon dioxide gas contained in the exhaust gas. By absorbing and immobilizing the carbon dioxide gas in the calcium-containing waste, it is possible to reduce the amount of carbon dioxide emitted into the atmosphere. An example of calcium-containing waste is waste concrete. The calcium-containing waste that has absorbed carbon dioxide may be used as a cement clinker raw material in the above-mentioned cement clinker production system. The calcium-containing waste that has absorbed carbon dioxide may be crushed, classified, etc., and used as roadbed material, concrete aggregate, etc. Furthermore, when the calcium-containing waste is waste concrete, only the paste component in the waste concrete that has absorbed carbon dioxide may be separated and recovered and used as a cement raw material.

[0053] In the above-mentioned methanation and carbonation of calcium-containing waste, by using the carbon dioxide-containing exhaust gas directly at a high temperature for methanation or carbonation of calcium-containing waste without purifying it (without separating or removing the carbon dioxide), methanation and carbonation of waste concrete can be carried out more efficiently. In the production of cement clinker using the cement clinker production system 1 described above, the carbon dioxide-containing exhaust gas generated in the calciner 4 may be stored and isolated as it is. [Example]

[0054] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. [Examples 1 to 6, Comparative Examples 1 to 6] Simulating the cement clinker production system of the present invention, the cement clinker raw materials were heated in a calciner under conditions such that the temperature of the cement clinker raw materials in the calciner and the oxygen concentration in a cyclone directly connected to the calciner were the values ​​shown in Table 1, thereby volatilizing the sulfur contained in the cement clinker raw materials. The mass of sulfur (converted to SO3) contained in the cement clinker raw materials before volatilization and the mass of sulfur (converted to SO3) contained in the cement clinker raw materials after volatilization were each measured using an X-ray fluorescence analyzer, and the sulfur volatilization rate {(mass of sulfur contained in the cement clinker raw materials before volatilization - mass of sulfur contained in the cement clinker raw materials after volatilization (converted to SO3)) / (mass of sulfur contained in the cement clinker raw materials before volatilization) × 100 (%)} was calculated. The results are shown in Table 1.

[0055] [Table 1]

[0056] A comparison of Examples 1 to 6 and Comparative Examples 1 to 6 in Table 1 shows that the sulfur volatilization rate can be increased by setting the temperature of the cement clinker raw material to 950°C or higher. It is also clear that the sulfur volatilization rate can be increased by setting the oxygen concentration in the cyclone to 2.0% by volume or less.

[0057] [Example 7] Using a thermogravimetric differential thermal analyzer, the temperature of the cement clinker raw material was raised from 20°C to 1,000°C at 20°C / min, and then cooled to 600°C at 20°C / min. The decarbonation rate was calculated from the change in weight. The results are shown in Figure 2. From Figure 2, it can be seen that the decarbonation rate of the cement clinker raw material can be maintained by maintaining the cyclone temperature at 880°C or higher. [Explanation of symbols]

[0058] 1. Cement clinker production system 2 Cyclone preheating device 2a, 2b, 2c, 2d Cyclone heat exchanger 3. Rotary Kiln 4 Calciner 4a Heating means 4b Fuel supply path 5 Clinker Cooler 6, 6a, 6b, 6c, 6d, 6e Kiln exhaust gas exhaust duct 7 Preheating raw material supply channel 8. Combustion-supporting gas supply device 9. Combustion-supporting gas supply line 10. Cyclone 11 Temperature measuring device 12 Calciner adjustment device 13 Decarbonation raw material supply route 14 Calciner exhaust gas discharge channel 15 Heat exchange equipment 16 Sulfur recovery unit 17 Sulfur-containing material washing equipment 18 Sulfur-containing material supply route 19 Sulfur-containing residue discharge path 20 First drainage channel 21 First wastewater treatment equipment 22 Dust collector 23 Quicklime-containing raw material washing equipment 24 Quicklime-containing raw material supply route 25 Raw material residue discharge path containing quicklime 26 Second drainage channel 27 Second wastewater treatment equipment 28 Merging passage 29 Chlorine Bypass Device 30 Oxygen concentration measuring device

Claims

1. a cyclone-type preheating device for preheating the cement clinker raw material; a rotary kiln for burning the cement clinker raw material preheated by the cyclone preheating device to obtain cement clinker; a calciner including a heating means disposed upstream of the rotary kiln together with the cyclone preheating device, for heating the cement clinker raw material using the heating means to promote decarbonation of the cement clinker raw material; a preheated raw material supply passage for supplying the preheated cement clinker raw material from the cyclone preheating device to the calciner; a clinker cooler disposed downstream of the rotary kiln for cooling the cement clinker; A kiln exhaust gas discharge path for discharging the kiln exhaust gas generated in the rotary kiln after passing through the cyclone type preheating device. A cement clinker production system comprising: a combustion-supporting gas supply device for supplying a combustion-supporting gas having an oxygen concentration higher than that of air; a combustion-sustaining gas supply path for introducing the combustion-sustaining gas from the combustion-sustaining gas supply device into the calciner; a cyclone directly connected to the calciner for separating the cement clinker raw material and the calciner exhaust gas discharged from the calciner; a temperature measuring device for measuring the temperature inside the cyclone; a calciner adjusting device for adjusting heating conditions of the cement clinker raw material in the calciner based on the temperature measured by the temperature measuring device; a decarbonation raw material supply path for supplying the separated cement clinker raw material from the cyclone to either or both of the cyclone type preheating device and the rotary kiln; a calciner exhaust gas discharge passage (which must be different from the kiln exhaust gas discharge passage) for discharging the separated calciner exhaust gas from the cyclone; a heat exchanger for exchanging heat between the calciner exhaust gas flowing through the calciner exhaust gas discharge passage and the combustion-supporting gas flowing through the combustion-supporting gas supply passage; a sulfur recovery device disposed in the calciner exhaust gas discharge passage and downstream of the heat exchanger for recovering sulfur-containing materials from the calciner exhaust gas; A cement clinker manufacturing method using a cement clinker manufacturing system including: A method for producing cement clinker, characterized in that heating conditions for the cement clinker raw materials in the calciner are adjusted so that the temperature of the cement clinker raw materials in the calciner is 975 to 1100°C, and the temperature in the cyclone is 880°C or higher and the oxygen concentration is 3.0% by volume or less.

2. A method for producing cement clinker as described in claim 1, wherein the temperature of the calciner exhaust gas flowing through the calciner exhaust gas discharge path is lowered to 150 to 400°C by the heat exchanger.

3. 3. The method for producing cement clinker according to claim 1, wherein the adjustment of the heating conditions is one or more adjustments selected from the oxygen concentration of the combustion-supporting gas, the amount of the combustion-supporting gas supplied to the heating means, and the amount of fuel supplied to the heating means.

4. 4. The method for producing cement clinker according to claim 1, wherein the sulfur recovery apparatus is a dry desulfurization apparatus including: a desulfurization agent supplying means for supplying a desulfurization agent to the calciner exhaust gas; and a sulfur-containing material recovery means for recovering, from the calciner exhaust gas, the sulfur-containing material that is a reaction product of the sulfur compounds in the calciner exhaust gas and the desulfurization agent.

5. a sulfur-containing material water washing device for washing the sulfur-containing material recovered by the sulfur recovery device; a sulfur-containing material supply line for supplying the sulfur-containing material from the sulfur recovery device to the sulfur-containing material water washing device; a sulfur-containing material residue discharge path for discharging sulfur-containing material residue generated in the sulfur-containing material water washing device; a first wastewater discharge passage for discharging wastewater generated in the sulfur-containing material washing apparatus; a first wastewater treatment device disposed in the first wastewater discharge channel for recovering heavy metals and solids from the wastewater; 5. The method for producing cement clinker according to claim 4, comprising:

6. 4. The method for producing cement clinker according to claim 1, wherein the sulfur recovery device is a wet desulfurization device including: a slurry preparation means for contacting the calciner exhaust gas with a liquid material to obtain a sulfur-containing slurry; and a solid-liquid separation means for performing solid-liquid separation of the sulfur-containing slurry to separate it into a solid and a liquid material containing the sulfur-containing material.

7. 7. The method for producing cement clinker according to claim 1, further comprising a confluence passage for confluence of a portion of the calciner exhaust gas flowing through the calciner exhaust gas discharge passage with the combustion-supporting gas flowing through the combustion-supporting gas supply passage.

8. A method for manufacturing cement clinker as described in Claim 7, wherein the confluence passage is located midway along the calciner exhaust gas discharge passage and is connected to the calciner exhaust gas discharge passage at a position downstream of the sulfur recovery device.

9. 9. The method for producing cement clinker according to claim 1, further comprising: extracting and cooling a portion of the exhaust gas generated in the rotary kiln without passing through the cyclone preheating device, removing solid components, discharging the exhaust gas from which the solid components have been removed, and classifying the solid components into coarse powder and fine powder, using the coarse powder as part of the cement clinker raw materials, and recovering the fine powder.

10. an oxygen concentration measuring device for measuring the oxygen concentration in the cyclone; 10. The method for producing cement clinker according to claim 1, wherein the calciner adjusting device adjusts heating conditions for the cement clinker raw materials in the calciner based on the temperature measured by the temperature measuring device and the oxygen concentration measured by the oxygen concentration measuring device.

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