Cement clinker and method for manufacturing cement clinker

Abstract

According to the present application, there is provided a cement firing apparatus and a method for manufacturing cement clinker using the same, which can suppress the amount of carbon dioxide emitted into the atmosphere, and can efficiently dry cement raw materials, and which is provided with a drying and pulverizing device for cement raw materials, a suspension preheater, a rotary kiln, a clinker cooler, a carbon dioxide recovery device, and a carbonation device.

Description

Technical Field

[0001] This invention relates to a cement firing equipment and a method for manufacturing cement clinker. Background Technology

[0002] In recent years, concerns about global warming have been growing, with calls to reduce carbon dioxide emissions into the atmosphere. Research is underway to separate and recover carbon dioxide from exhaust gases produced by various facilities, including power plants, incinerators, cement plants, steel mills, and factory equipment, in order to reduce emissions of carbon dioxide-containing exhaust gases into the atmosphere. Reducing carbon dioxide emissions from cement plants is considered a particularly important issue.

[0003] As a typical component of a cement plant, the cement manufacturing equipment disclosed in Patent Document 1 can be cited as an example. This equipment includes: a preheater that preheats cement raw materials by exchanging heat with high-temperature gas; a cement kiln that kilns the cement raw materials to produce cement clinker; a cooling device that guides part of the high-temperature air that has exchanged heat with the cement clinker as combustion air for the burner of the cement kiln; an absorption tower and a regeneration tower, the absorption tower storing an absorbent liquid that absorbs carbon dioxide, and the regeneration tower causing the carbon dioxide to volatilize by heating the absorbent liquid; and an exhaust inlet pipe that guides exhaust gas from the preheater to the absorption tower after utilizing the regeneration tower as a heating source.

[0004] As a suspended preheater, for example, there is a heating device with the structure shown in Patent Document 2, in which multiple independent hot gases flow through multiple air ducts composed of multiple dust collectors, and on the other hand, powdery substances are introduced from the air duct of the dust collector leading to the uppermost dust collector, so that they pass through the dust collector in sequence and are discharged from the lower part of the lowermost dust collector.

[0005] Furthermore, Patent Document 3 discloses a cement clinker manufacturing system, comprising: a cyclone preheating device for preheating cement clinker raw materials; a rotary kiln for calcining the preheated cement clinker raw materials to obtain cement clinker; a calcining furnace disposed on the front flow side of the rotary kiln to promote decarbonation of the cement clinker raw materials; a preheated raw material supply path for supplying cement clinker raw materials from the preheating device to the calcining furnace; a clinker cooler for cooling the cement clinker; a kiln exhaust discharge path for discharging exhaust gas generated in the rotary kiln after passing through the preheating device; and a calcining furnace grate. The system includes: a gas discharge path for discharging carbon dioxide-containing exhaust gas generated in the calcining furnace; a combustion-supporting gas supply device for increasing the oxygen concentration; a first recovery component for recovering quicklime-containing raw materials from the carbon dioxide-containing exhaust gas; a combustion-supporting gas supply path for exchanging heat between the carbon dioxide-containing exhaust gas and the combustion-supporting gas on a flow side further forward than the first recovery component; and a calcining furnace exhaust gas supply path for merging a portion of the carbon dioxide-containing exhaust gas with the combustion-supporting gas on a flow side further backward than the first recovery component of the calcining furnace exhaust gas supply path.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 9-110485

[0009] Patent Document 2: Japanese Patent Application Publication No. 55-22322

[0010] Patent Document 3: Japanese Patent Application Publication No. 2022-148255 Summary of the Invention

[0011] The technical problem to be solved by the invention

[0012] The purpose of this invention is to provide a cement firing equipment and a method for manufacturing cement clinker that can suppress carbon dioxide emissions into the atmosphere and efficiently dry cement raw materials.

[0013] means for solving technical problems

[0014] To address the aforementioned issues, the present invention provides the following cement firing equipment.

[0015] 1. A cement firing device, comprising:

[0016] Drying and pulverizing equipment, which dries and pulverizes cement raw materials to produce powdered raw materials;

[0017] A suspension preheater is used to preheat and calcine the powder raw materials;

[0018] A rotary kiln, which fires the preheated and calcined powdered raw materials to produce cement clinker;

[0019] A cement clinker cooler for cooling the cement clinker;

[0020] A carbon dioxide recovery device that recovers carbon dioxide contained in the combustion exhaust gas discharged from the suspension preheater; and

[0021] A carbonation device that produces a powder containing calcium carbonate by reacting combustion exhaust gas discharged from the suspension preheater with a powder containing calcium oxide.

[0022] The suspended preheater, serving as a preheater, has the following characteristics:

[0023] A calcining furnace, which calcines the powdered raw material;

[0024] Two distinct air ducts: a calciner system air duct through which the combustion exhaust gas from the calciner passes and a kiln system air duct through which the combustion exhaust gas from the rotary kiln passes.

[0025] The combustion exhaust outlet of the calcining furnace, which discharges from the suspension preheater through the air duct of the calcining furnace system, contains the combustion exhaust gas from the calcining furnace that has preheated and calcined the powder raw materials; and

[0026] The kiln combustion exhaust outlet is the kiln combustion exhaust that is discharged from the suspension preheater and passes through the kiln system air duct to preheat and calcine the powder raw materials;

[0027] The cement firing equipment also includes:

[0028] An exhaust duct includes: a calcining furnace combustion exhaust duct for supplying calcining furnace combustion exhaust discharged from the calcining furnace combustion exhaust outlet to the carbon dioxide recovery device; a kiln combustion exhaust duct for supplying kiln combustion exhaust discharged from the kiln combustion exhaust outlet to the drying equipment of the drying and pulverizing device; a carbonation device gas supply duct for supplying kiln combustion exhaust passing through the kiln combustion exhaust duct to the carbonation device; and a carbonation device exhaust duct for supplying kiln combustion exhaust discharged from the carbonation device to the kiln combustion exhaust duct.

[0029] The separating device and the first powder supply device are used to separate the powder raw material after preheating and calcination from the suspension preheater, and the first powder supply device is used to supply the powder raw material separated by the separating device as a powder containing the calcium oxide to the carbonation device.

[0030] The device includes an exhaust system, a powder material separation device, and a second powder material supply device. The exhaust system extracts the kiln combustion exhaust before the cyclone dust collector at the bottom of the kiln system duct supplied to the suspension preheater. The powder material separation device separates the powder material contained in the kiln combustion exhaust extracted by the exhaust system. The second powder material supply device supplies the powder material separated by the powder material separation device as a powder containing the calcium oxide to the carbonation device.

[0031] The present invention provides the following cement firing equipment as a preferred embodiment.

[0032] 2. The method for manufacturing cement clinker according to 1 above, wherein,

[0033] The separating device is installed in the powder material conduit that supplies the powder raw material, which has been preheated and calcined by the suspension preheater, to the rotary kiln.

[0034] 3. The cement firing equipment according to 1 or 2 above further comprises:

[0035] A powder raw material supply device that supplies the powder raw material discharged from the drying and pulverizing device to the suspension preheater; and a powder material conveying device generated by the carbonation device that merges the powder material containing the calcium carbonate generated by the carbonation device with the powder raw material discharged from the drying and pulverizing device.

[0036] 4. The cement firing equipment according to claim 3 above further comprises:

[0037] A powder raw material mixture collection device for collecting a mixture of powder containing calcium carbonate conveyed by the powder conveying device generated by the carbonation device and powder raw materials discharged from the drying and pulverizing device; a chemical composition determination device for determining the chemical composition of the powder raw material mixture collected by the powder raw material mixture collection device; and a cement raw material blending device for adjusting the proportion of the cement raw materials according to the determination results of the chemical composition determination device.

[0038] 5. The cement firing equipment according to any one of 1 to 4 above, wherein,

[0039] The carbonation device is a fluidized bed reactor.

[0040] Furthermore, the present invention provides a method for manufacturing the following cement clinker.

[0041] 6. A method for manufacturing cement clinker, wherein the cement firing equipment described in any one of 1 to 5 above is adjusted according to any one of the following conditions (i) to (iii).

[0042] (i) Adjust the supply rate of powdered raw materials to the suspension preheater;

[0043] (ii) Adjust the fuel supply to the rotary kiln;

[0044] (iii) Adjust the water spray volume into the exhaust duct of the kiln combustion.

[0045] 7. The method for manufacturing cement clinker according to 6 above, wherein,

[0046] According to the conditions, the temperature of the kiln combustion exhaust gas discharged from the kiln combustion exhaust outlet is adjusted to be above 250°C and below 600°C.

[0047] Invention Effects

[0048] According to the present invention, a cement calcining device and a method for manufacturing cement clinker are provided that can suppress carbon dioxide emissions into the atmosphere and efficiently dry cement raw materials. Attached Figure Description

[0049] Figure 1 This is a schematic diagram illustrating a preferred embodiment of the cement firing equipment according to this invention.

[0050] Figure 2 This is a schematic diagram illustrating a preferred embodiment of the suspension preheater used in the cement firing equipment of this embodiment.

[0051] Figure 3 This is a schematic diagram illustrating a preferred embodiment of the carbonation apparatus used in the cement firing equipment of this embodiment.

[0052] Figure 4 This is a schematic diagram used to illustrate the results of the embodiments.

[0053] Figure 5 This is a schematic diagram used to illustrate the results of the comparative example. Detailed Implementation

[0054] Hereinafter, embodiments of the present invention (hereinafter sometimes referred to as "this embodiment") will be described. The present invention is not limited to the following embodiments, and can be implemented by arbitrary modifications without affecting the effect of the invention. Furthermore, the expression "AA~BB" in this specification refers to "AA and above and BB and below". Also, in this specification, the values ​​involved in "above", "below", and "~" related to the description of the numerical range are values ​​that can be arbitrarily combined. For example, when a certain numerical range is described as "CC~DD" and "EE~FF", it also includes numerical ranges such as "CC~FF" and "EE~DD".

[0055] Cement calcination equipment

[0056] The cement firing equipment of this embodiment includes:

[0057] Drying and pulverizing equipment, which dries and pulverizes cement raw materials to produce powdered raw materials;

[0058] A suspension preheater is used to preheat and calcine the powder raw materials;

[0059] A rotary kiln, which fires the preheated and calcined powdered raw materials to produce cement clinker;

[0060] A cement clinker cooler for cooling the cement clinker;

[0061] A carbon dioxide recovery device that recovers carbon dioxide contained in the combustion exhaust gas discharged from the suspension preheater; and

[0062] A carbonation device that produces a powder containing calcium carbonate by reacting combustion exhaust gas discharged from the suspension preheater with a powder containing calcium oxide.

[0063] The suspended preheater, serving as a preheater, has the following characteristics:

[0064] A calcining furnace, which calcines the powdered raw material;

[0065] Two distinct air ducts: a calciner system air duct through which the combustion exhaust gas from the calciner passes and a kiln system air duct through which the combustion exhaust gas from the rotary kiln passes.

[0066] The combustion exhaust outlet of the calcining furnace, which discharges from the suspension preheater through the air duct of the calcining furnace system, contains the combustion exhaust gas from the calcining furnace that has preheated and calcined the powder raw materials; and

[0067] The kiln combustion exhaust outlet is the kiln combustion exhaust that is discharged from the suspension preheater and passes through the kiln system air duct to preheat and calcine the powder raw materials;

[0068] The cement firing equipment also includes:

[0069] An exhaust duct includes: a calcining furnace combustion exhaust duct for supplying calcining furnace combustion exhaust discharged from the calcining furnace combustion exhaust outlet to the carbon dioxide recovery device; a kiln combustion exhaust duct for supplying kiln combustion exhaust discharged from the kiln combustion exhaust outlet to the drying equipment of the drying and pulverizing device; a carbonation device gas supply duct for supplying kiln combustion exhaust passing through the kiln combustion exhaust duct to the carbonation device; and a carbonation device exhaust duct for supplying kiln combustion exhaust discharged from the carbonation device to the kiln combustion exhaust duct.

[0070] A separating device and a first powder supply device, wherein the separating device separates the preheated and calcined powder raw material from the suspension preheater, and the first powder supply device supplies the powder raw material separated by the separating device as a powder containing the calcium oxide to the carbonation device; and

[0071] The system includes an exhaust device, a powder raw material separation device, and a second powder supply device. The exhaust device extracts the kiln combustion exhaust before the cyclone dust collector at the bottom of the kiln system duct supplied to the suspension preheater. The powder raw material separation device separates the powder raw material contained in the kiln combustion exhaust extracted by the exhaust device. The second powder supply device supplies the powder raw material separated by the powder raw material separation device as a powder containing the calcium oxide to the carbonation device.

[0072] The cement firing equipment disclosed in Patent Document 1 is as follows: exhaust gas from a preheater, which preheats cement raw materials by exchanging heat with high-temperature gas, is guided to an absorption tower after being used as a heating source via a regeneration tower. This utilizes the thermal energy of the exhaust gas generated in the cement manufacturing equipment to inexpensively remove carbon dioxide from the exhaust gas. However, since the absorption tower is used to recover carbon dioxide from the total amount of exhaust gas discharged from the preheater, the concentration of carbon dioxide in the exhaust gas targeted for recovery is low. Therefore, it cannot be said that the carbon dioxide recovery efficiency of the equipment is high, and there is room for improvement in this regard. Furthermore, it is also lacking from the viewpoint of efficiently drying cement raw materials.

[0073] The suspension preheater disclosed in Patent Document 2 achieves a significant reduction in thermal and electrical energy consumption during heating by miniaturizing the exhaust fan through improved thermal efficiency. While it does indeed achieve improved and excellent thermal efficiency, it assumes that the hot gas used to heat powdered materials (powdered cement raw materials) in the suspension preheater is exhausted from the exhaust fan. Further improvements are possible in reducing carbon dioxide emissions.

[0074] The cement clinker manufacturing system disclosed in Patent Document 3 does not include any research on the heat utilization of kiln exhaust gas emitted into the atmosphere. Furthermore, there is room for further improvement in reducing the amount of carbon dioxide contained in the kiln exhaust gas, i.e., the amount of carbon dioxide emitted into the atmosphere.

[0075] Generally, cement firing equipment emits carbon dioxide of energy origin, generated from the fuel used in the suspension preheater and rotary kiln. In addition, it also emits non-energy-origin carbon dioxide generated from powdered raw materials. Furthermore, the ratio of energy-origin to non-energy-origin carbon dioxide is approximately 40:60. Therefore, in order to reduce carbon dioxide emissions from cement firing equipment into the atmosphere, research is needed on both energy-origin and non-energy-origin carbon dioxide. The inventors have conducted research, particularly on reducing non-energy-origin carbon dioxide.

[0076] First, the inventors focused on the following characteristic: the combustion exhaust from the calciner furnace of the suspension preheater, which serves as the heat source, contains a higher carbon dioxide content than the combustion exhaust from the rotary kiln. Furthermore, since the combustion exhaust from the calciner furnace has a higher carbon dioxide content than the combustion exhaust from the kiln, it is believed that recovering carbon dioxide from the combustion exhaust from the calciner furnace helps improve the carbon dioxide recovery efficiency. Moreover, in the suspension preheater, the calcium component contained in the powdered raw material is decarbonated to become calcium oxide. Therefore, it is believed that by using the carbon dioxide contained in the kiln combustion exhaust for the carbonation of calcium oxide contained in the powdered raw material, it is possible to recover the carbon dioxide contained in the kiln combustion exhaust, thereby reducing carbon dioxide emissions into the atmosphere.

[0077] Based on the above research, by installing a carbon dioxide recovery device and a carbonation device in the cement calcining equipment, and supplying combustion exhaust from the calcining furnace to the carbon dioxide recovery device and kiln combustion exhaust to the carbonation device, the emission of carbon dioxide into the atmosphere is suppressed. Furthermore, since the carbonation reaction is exothermic and its temperature is maintained, the kiln combustion exhaust supplied to the carbonation device is effectively utilized for drying the powdered raw materials. Thus, a cement calcining equipment and a method for manufacturing cement clinker that can suppress carbon dioxide emissions into the atmosphere and also efficiently dry cement raw materials are completed.

[0078] The following uses Figure 1 The cement firing equipment and cement clinker manufacturing method of this embodiment will be described. Figure 1 This is a schematic diagram illustrating a preferred embodiment of the cement firing equipment according to this invention.

[0079] exist Figure 1The diagram shows that the cement calcining equipment includes: a suspension preheater 1 for drying and pulverizing cement raw materials into powder by a drying and pulverizing device, and for preheating and calcining the powder raw materials; a rotary kiln for calcining the powder raw materials into cement clinker; and a cement clinker cooler for cooling the cement clinker.

[0080] Regarding the carbonation apparatus, the following is shown: the powder raw material that has been preheated and calcined in the suspension preheater 1 is supplied to the carbonation apparatus as calcium oxide-containing powder via the separation device 12 and the first powder supply device 13; before the cyclone dust collector K1 at the lowest section of the kiln system duct supplied to the suspension preheater 1, the kiln combustion exhaust is drawn by the extraction device 8, and the powder raw material separated by the powder raw material separation device 9 is supplied to the carbonation apparatus as calcium oxide-containing powder via the second powder supply device 10; and the kiln combustion exhaust that passes through the kiln combustion exhaust exhaust duct of the suspension preheater 1 as combustion exhaust is supplied to the carbonation apparatus via the kiln combustion exhaust outlet 4, the kiln combustion exhaust discharge duct 6, and the carbonation apparatus gas supply duct 7.

[0081] exist Figure 1 As shown, the kiln combustion exhaust gas used in the carbonation unit is supplied to the kiln combustion exhaust exhaust duct 6 via the carbonation unit exhaust duct 14. The kiln combustion exhaust gas is used as a heat source in the drying unit of the drying and pulverizing unit and is finally discharged into the atmosphere via the dust collector and chimney.

[0082] Furthermore, the calcium carbonate-containing powder generated in the carbonation unit is fed to the suspension preheater 1 via the carbonation unit powder conveying device 15, together with the powder raw material discharged from the drying and pulverizing unit, as a powder raw material mixture, and then preheated and calcined via the powder raw material supply device 16. A cement raw material blending device is also shown, wherein a portion of the powder raw material mixture discharged from the drying and pulverizing unit and the calcium carbonate-containing powder generated in the carbonation unit is collected by the powder raw material mixture collection device 17, analyzed in the chemical composition measuring device 18, and the proportions of cement raw materials (Ca, Si, Al, and Fe raw materials) are adjusted based on the measurement results.

[0083] [Suspension preheater]

[0084] The cement calcining equipment of this embodiment includes a suspension preheater comprising: a calcining furnace for calcining the powdered raw material; two distinct air ducts, namely a calcining furnace system air duct through which calcining furnace combustion exhaust from the calcining furnace passes and a kiln system air duct through which kiln combustion exhaust from the rotary kiln passes; a calcining furnace combustion exhaust outlet, which discharges from the suspension preheater the calcining furnace combustion exhaust that has preheated and calcined the powdered raw material through the calcining furnace system air duct; and a kiln combustion exhaust outlet, which discharges from the suspension preheater the kiln combustion exhaust that has preheated and calcined the powdered raw material through the kiln system air duct.

[0085] As long as the suspension preheater has two air ducts that are different from the aforementioned calcining furnace, calcining furnace system air duct, and kiln system air duct, as well as the calcining furnace combustion exhaust outlet and the kiln combustion exhaust outlet, there are no special restrictions on other structures. Figure 2 A preferred embodiment of the suspension preheater will be described.

[0086] exist Figure 2 The diagram shows that the suspension preheater has four cyclone dust collectors (C1-C4 and K1-K4) for collecting powdered raw materials and gas flow paths (C0a-C4a and K0a-K4a) that connect the four cyclone dust collectors in sequence. It also has two independent air ducts (calciner system flow path and kiln system flow path) for the independent passage of different exhaust gases. In the calciner system air duct and the kiln system air duct, the different combustion exhaust gases from the calciner and kiln pass independently. The calciner combustion exhaust gas passes through gas flow paths C0a-C4a and sequentially through the lowest cyclone dust collector C1 to the highest cyclone dust collector C4. The kiln combustion exhaust gas passes through gas flow paths K1a-K4a and sequentially through the lowest cyclone dust collector K1 to the highest cyclone dust collector K4.

[0087] exist Figure 2 As shown, the combustion exhaust from the calcining furnace passes through the calcining furnace system duct of the suspension preheater 1 and is discharged from the calcining furnace combustion exhaust outlet 3. The combustion exhaust from the kiln passes through the kiln system duct and is discharged from the kiln combustion exhaust outlet 4. Furthermore, as... Figure 2 As shown, the combustion exhaust from the calcining furnace and the combustion exhaust from the kiln are supplied to their respective uses via the combustion exhaust exhaust duct 5 from the calcining furnace and the combustion exhaust exhaust duct 6 from the kiln.

[0088] Thus, by using two independent air ducts with different exhaust gases, the combustion exhaust from the calcining furnace and the combustion exhaust from the kiln can be treated separately. Therefore, the combustion exhaust from the calcining furnace, which has a high carbon dioxide content, can recover carbon dioxide more efficiently through the carbon dioxide recovery device. Furthermore, the combustion exhaust from the kiln is supplied to the carbonation unit for the carbonation of calcium oxide contained in the powder raw materials, thereby recovering carbon dioxide and reducing carbon dioxide emissions into the atmosphere.

[0089] And, as Figure 2 As shown, it is preferable to have induced draft fans (calciner combustion exhaust induced draft fan and kiln combustion exhaust induced draft fan) in two independent air ducts with different exhaust gases. Furthermore, it is also preferable to have a flow rate regulating damper (not shown). By having induced draft fans and flow rate regulating dampers, the flow rate and pressure of the combustion exhaust gases can be easily adjusted. In particular, regarding the kiln combustion exhaust air duct, it is preferable to install induced draft fans and flow rate regulating dampers to adjust the flow rate to the downstream carbonation unit and drying and pulverizing unit.

[0090] For powder raw materials, in Figure 2 The diagram shows raw material conduits that have the following characteristics: raw material conduits K2b to K4b connecting the cyclone dust collector of the kiln system duct and the gas flow path of the cyclone dust collector of the calciner system duct that supplies combustion exhaust from the calciner to the cyclone dust collector of the calciner system duct at the same section as the cyclone dust collector of the kiln system duct; raw material conduits K1b of the kiln system duct connecting the cyclone dust collector of the lowest section of the kiln system duct and the raw material conduit of the calciner; raw material conduits C2b to C4b of the kiln system duct connecting the cyclone dust collector of the calciner system duct and the gas flow path of the cyclone dust collector of the kiln system duct that supplies combustion exhaust from the kiln to the cyclone dust collector of the calciner system duct at the next section of the kiln system duct; and raw material conduits C1b of the calciner system duct connecting the cyclone dust collector of the lowest section of the calciner system duct and the raw material conduit of the rotary kiln.

[0091] The powder raw material discharged from the drying and pulverizing unit, mixed with the powder containing calcium carbonate generated in the carbonation unit, is supplied to the suspension preheater 1 via the powder raw material supply device 16. More specifically, it is supplied from the powder raw material supply device 16 to the cyclone dust collector at the uppermost section of the suspension preheater 1. Figure 2 As shown, the powder raw material mixture, which becomes powder raw material, is supplied from the powder raw material supply device 16K of the kiln system to the cyclone dust collector K4 at the top of the kiln system air duct, and from the powder raw material supply device 16C of the calcining furnace system to the cyclone dust collector C4 at the top of the calcining furnace system air duct.

[0092] Then, the powder raw material mixture supplied from the powder raw material supply device 16K of the kiln system is preheated and calcined by passing sequentially through 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, calcining furnace, gas flow path C0a, cyclone dust collector C1 and raw material conduit C1b, and then supplied to the rotary kiln.

[0093] Furthermore, the powder raw materials supplied from the powder raw material supply device 16C of the calcining furnace system are supplied to the cyclone dust collector C4, and together with the powder raw materials supplied from the powder raw material supply device 16K of the kiln system, they are preheated and calcined through the raw material conduit C4b to the raw material conduit C1b, and then supplied to the rotary kiln.

[0094] In this way, the powdered raw material supplied to the suspension preheater 1 moves alternately from top to bottom through the cyclone dust collectors in the calciner system duct and the kiln system duct, which are separate ducts, and is then supplied to the rotary kiln after passing through all the cyclone dust collectors. Furthermore, the powdered raw material moving step by step from the top to the bottom of the cyclone dust collectors comes into contact with the combustion exhaust (calciner combustion exhaust and kiln combustion exhaust) moving in the opposite direction, i.e., from the bottom cyclone dust collector towards the top cyclone dust collector, within the duct, thereby enabling efficient preheating and calcination.

[0095] The powder raw material supply device 16 of the cement calcining equipment of this embodiment can adopt the same form as the powder raw material supply device of conventional cement calcining equipment. For example, the powder raw material supply device 16 preferably includes: piping for supplying powder raw material discharged from the drying and pulverizing device to the suspension preheater 1; and a mixing device for mixing the powder raw material and calcium carbonate-containing powder material conveyed from the carbonation device through the carbonation device powder material conveying device 15 to prepare a powder raw material mixture.

[0096] Furthermore, in addition to the piping through which the supplied or transported material passes, the powder raw material supply device 16 and the powder conveying device 15 generated by the carbonation device may also be equipped with a feeder or other equipment for pressure conveying, as needed.

[0097] [Carbonation unit]

[0098] The cement firing equipment of this embodiment includes a carbonation unit, which produces a calcium carbonate-containing powder by reacting combustion exhaust gas discharged from the suspension preheater 1 with a powder containing calcium oxide. Figure 3 The carbonation apparatus is described.

[0099] Figure 3 This is a schematic diagram illustrating a preferred embodiment of the carbonation apparatus. Figure 3 The carbonation unit includes: a carbonation reaction tower in which kiln combustion exhaust gas reacts with powder containing calcium oxide; a dust collector that separates the carbonation unit-generated powder contained in the kiln combustion exhaust gas discharged from the carbonation reaction tower from the kiln combustion exhaust gas; a carbonation unit induced draft fan for discharging the kiln combustion exhaust gas from the dust collector and supplying it to a drying unit; and a fluidization pressurized blower for fluidizing the kiln combustion exhaust gas discharged from the dust collector and recovering it to the carbonation reaction tower.

[0100] (Combustion exhaust)

[0101] Combustion exhaust gas is supplied to the carbonation unit via kiln combustion exhaust gas discharge duct 6 and carbonation unit gas supply duct 7. Kiln combustion exhaust gas discharge duct 6 is used to supply the kiln combustion exhaust gas discharged from the kiln combustion exhaust gas outlet to the drying equipment of the drying and pulverizing unit. Carbonation unit gas supply duct 7 is used to supply the kiln combustion exhaust gas passing through the kiln combustion exhaust gas discharge duct to the carbonation unit. That is, the combustion exhaust gas used in the carbonation unit is kiln combustion exhaust gas.

[0102] The flow rate of kiln combustion exhaust supplied to the carbonation unit (the flow rate of kiln combustion exhaust to the air supply duct 7 of the carbonation unit) and the flow rate of kiln combustion exhaust supplied directly to the drying unit (the flow rate of kiln combustion exhaust to the exhaust duct 6 of the kiln combustion exhaust) can be arbitrarily allocated. This allows for the regulation of the amount of carbon dioxide emitted into the atmosphere. Furthermore, the total amount of kiln combustion exhaust can be supplied to the carbonation unit.

[0103] The distribution of the kiln combustion exhaust flow rate can be adjusted by considering factors such as the amount of kiln combustion exhaust discharged from the suspension preheater 1, the amount of cement raw material to be dried in the drying unit of the drying and pulverizing device, and the amount of calcium oxide-containing powder. This can be achieved by adjusting the airflow regulating baffle and the induced draft fan of the carbonation unit. For example, when the carbon dioxide content in the kiln combustion exhaust is extremely low, the power consumption of the induced draft fan of the carbonation unit can be reduced by decreasing the amount of gas supplied to the carbonation unit.

[0104] The kiln combustion exhaust gas supplied to the carbonation unit is supplied from the suspension preheater 1 via the kiln combustion exhaust outlet 4 and the kiln combustion exhaust outlet duct 6. Therefore, the exhaust temperature of the kiln combustion exhaust gas supplied to the carbonation unit is the same as the exhaust temperature from the suspension preheater 1. The temperature of the kiln combustion exhaust gas supplied to the carbonation unit is preferably set to 250°C or higher, and preferably 600°C or lower. A temperature of 250°C or higher allows for efficient drying of cement raw materials, while a temperature of 600°C or lower facilitates increasing the carbonation efficiency of calcium oxide in the carbonation unit to 100%.

[0105] Methods for adjusting the temperature of the kiln combustion exhaust supplied to the carbonation unit include, for example, the following methods (i) to (iii), which can be performed individually or in combination.

[0106] (i) Adjust the amount of powdered raw material supplied to the suspension preheater 1. By increasing the amount of powdered raw material, the kiln combustion exhaust temperature can be reduced and the temperature of the kiln combustion exhaust supplied to the carbonation unit can be reduced.

[0107] (ii) Adjusting the fuel supply to the rotary kiln. By increasing the amount of fuel, the temperature of the kiln combustion exhaust supplied to the carbonation unit can be increased. Furthermore, the temperature of the kiln combustion exhaust supplied to the carbonation unit can also be increased, for example, by feeding calorific waste materials such as waste clay, waste tires, and waste plastics into the raw material conduit (located near the calciner).

[0108] (iii) Adjust the water spray volume into the kiln combustion exhaust duct (specifically, any part from the kiln combustion exhaust outlet 4 to the kiln combustion exhaust duct 6). By adjusting the water spray volume, the temperature fluctuation of the kiln combustion exhaust supplied to the carbonation unit can be adjusted. Here, industrial water, tap water, and waste such as liquid waste such as waste acid and waste alkali, and high-moisture waste such as sewage sludge can also be used for spraying.

[0109] The kiln combustion exhaust used in the carbonation unit consumes carbon dioxide through the carbonation reaction of calcium oxide, resulting in exhaust with reduced carbon dioxide content. Furthermore, since this carbonation reaction is exothermic, the temperature of the kiln combustion exhaust discharged from the carbonation unit also increases, depending on the supply temperature of the kiln combustion exhaust to the carbonation unit. Although the temperature of the kiln combustion exhaust supplied to the carbonation unit decreases due to heat loss from the kiln combustion exhaust exhaust duct, it increases in temperature through the aforementioned exothermic reaction, thus enabling it to be used as a heat source for drying cement raw materials in the drying unit of the drying and pulverizing unit.

[0110] Furthermore, as will be described later, when a fluidized bed type is used as the carbonation reaction tower, it is preferable to recover the kiln combustion exhaust gas discharged from the carbonation unit and use it for the formation of the fluidized bed. The distribution of the flow rate of the kiln combustion exhaust gas discharged from the carbonation unit can be determined by considering the operating conditions of the cement firing equipment, and can be done using a baffle for air volume regulation.

[0111] (Powder containing calcium oxide)

[0112] The calcium oxide-containing powder supplied to the carbonation unit is the powder raw material (hereinafter also referred to as "Powder Raw Material 1") which is preheated and calcined in the suspension preheater and supplied to the rotary kiln, and the powder raw material contained in the kiln combustion exhaust before being supplied from the rotary kiln to the suspension preheater 1 (hereinafter also referred to as "Powder Raw Material 2").

[0113] The powder raw material 1 is supplied to the carbonation unit via a separating device 12 that separates the powder raw material after preheating and calcination in the suspension preheater 1 and a first powder supply device 13 for supplying the powder raw material separated by the separating device 12 to the carbonation unit.

[0114] Since the calcium carbonate contained in the powder raw material supplied to the suspension preheater 1 is preheated and calcined, and releases carbon dioxide through the decarbonation reaction (CaCO3→CaO+CO2) while becoming calcium oxide, the powder raw material 1 will contain a large amount of calcium oxide.

[0115] In the carbonation unit, the calcium oxide contained in powder raw material 1 adsorbs carbon dioxide contained in the kiln combustion exhaust and undergoes carbonation, thereby reducing the carbon dioxide content in the kiln combustion exhaust. Therefore, as powder raw material 1, it is preferable to use powder raw material discharged from the lower-level cyclone dust collector, as it has a higher calcium oxide content. In the suspension preheater 1, the powder raw material undergoes a decarbonation reaction as it moves towards the lower-level cyclone dust collector, thus increasing the calcium oxide content. (Before being fed into the calcining furnace 2...) Figure 2 The decarbonation rate of the powdered raw material (using conduit K1b) is about 10%, from the lowest section of the cyclone dust collector ( Figure 2 The decarbonation rate of the powder raw material discharged from the cyclone dust collector C1 and the raw material conduit C1b is about 90%, and the calcium oxide content in the powder raw material increases dramatically after passing through the calcination furnace. Therefore, as powder raw material 1, it is more preferable to use the powder raw material discharged from the cyclone dust collector at the bottom.

[0116] Therefore, as Figure 2As shown, the separating device 12 is preferably located in the powder material conduit 11, C1b that supplies the powder material preheated and calcined by the suspension preheater 1 to the rotary kiln, that is, the powder material conduit 11, C1b located between the cyclone dust collector C1 at the lowest section of the air duct of the calcining furnace system and the rotary kiln.

[0117] Regarding the powdered raw material 2 contained in the kiln combustion exhaust supplied from the rotary kiln to the suspension preheater 1, the decarbonation rate of calcium carbonate in the powdered raw material (powdered raw material mixture) supplied to the suspension preheater 1 reaches nearly 100%, meaning that the total amount of calcium carbonate is converted into calcium oxide. Therefore, as already described, in the carbonation unit, the carbon dioxide content in the kiln combustion exhaust can be reduced extremely efficiently through the carbonation reaction (CaO + CO2 → CaCO3) with carbon dioxide contained in the kiln combustion exhaust.

[0118] The decarbonation rate in this specification is a value that can be calculated using the following formula.

[0119] Decarbonation rate (%) = (Ca0 - Ca1) / Ca0 × 100

[0120] Ca0: The amount of calcium carbonate (ton / h) contained in the powdered raw material fed into the suspension preheater.

[0121] Ca1: The amount of calcium carbonate (ton / h) contained in the powdered raw material in cyclone dust collector C1.

[0122] Furthermore, the powdered raw material 2 is supplied to the carbonation unit via the following devices: an exhaust device 8, which extracts kiln combustion exhaust before the cyclone dust collector at the lowest section of the kiln system duct supplied to the suspension preheater; a powdered raw material separation device 9, which separates the powdered raw material contained in the kiln combustion exhaust extracted by the exhaust device 8; and a second powder supply device 10, which supplies the powdered raw material separated by the powdered raw material separation device 9 to the carbonation unit.

[0123] As a calcium oxide-containing powder supplied to the carbonation unit, powder raw material 1 can be supplied alone, powder raw material 2 can be supplied alone, or both powder raw material 1 and powder raw material 2 can be supplied simultaneously. As already described, the decarbonation rate of powder raw material 1 supplied to the rotary kiln becomes lower than the decarbonation rate of powder raw material 2 contained in the kiln combustion exhaust gas supplied from the rotary kiln to the suspension preheater 1. Therefore, as a calcium oxide-containing powder, it is preferable to use at least powder raw material 2.

[0124] On the other hand, the amount of powder raw material 1 used can be adjusted arbitrarily within a range that does not affect the production of cement clinker. For example, if supplying only powder raw material 2 would result in insufficient calcium oxide, thus failing to adequately reduce the carbon dioxide content in the kiln combustion exhaust, measures can be taken to use powder raw material 1 or increase the amount of powder raw material 1 used.

[0125] There are no particular restrictions on the location of the exhaust device 8, as long as it is a location that can extract kiln combustion exhaust before the cyclone dust collector at the bottom of the kiln system air duct supplied to the suspension preheater. It can be set at any location that connects the cyclone dust collector K1 at the bottom of the suspension preheater 1, which is where the kiln combustion exhaust supplied from the rotary kiln first enters, and the gas flow path K0a of the rotary kiln.

[0126] As for the extraction device used in the extraction device 8, any conventionally used device, such as a suction nozzle, can be used. Similarly, as for the separation device used in the powder raw material separation device 9, any conventionally used device, such as a cyclone dust collector, can be used.

[0127] (Carbonization reaction tower)

[0128] As a carbonation reaction tower, any reaction tower capable of producing calcium carbonate powder by reacting the combustion exhaust gas discharged from the suspension preheater 1 with the powder containing calcium oxide can be used without particular restrictions.

[0129] For example, a simple reaction tower can be used to generate calcium carbonate by blowing calcium oxide powder into the duct through which the kiln combustion exhaust flows. A reaction tower that further extends the contact time between the calcium oxide powder and the kiln combustion exhaust, thereby improving reaction efficiency, can also be used. As a device that can improve reaction efficiency, examples such as... Figure 3 The diagram shows a fluidized bed-type carbonation reaction tower that uses kiln combustion exhaust gas to agitate calcium oxide-containing powder, ensuring sufficient reaction time. This improves the efficiency of the carbonation reaction, increases the calcium carbonate formation rate, and thus reduces the amount of calcium oxide-containing powder required. Consequently, it effectively reduces the carbon dioxide content in the kiln combustion exhaust gas, thereby more effectively suppressing carbon dioxide emissions into the atmosphere.

[0130] exist Figure 3 As shown, the kiln combustion exhaust gas supplied to the carbonation reaction tower is split into two streams by a gas distributor and supplied from two directions, but it is not limited to this. For example, it can also be supplied from one direction, and it can also be supplied from three, four, or more directions. Among these, it is preferable to supply from two directions if it is considered that a swirling flow can be generated more effectively.

[0131] At this point, it is preferable to supply the kiln combustion exhaust gas into the carbonation reaction tower in a manner that generates a swirling flow. This ensures a longer contact time between the calcium oxide-containing powder and the kiln combustion exhaust gas, thereby improving the reaction efficiency of calcium oxide with the carbon dioxide contained in the kiln combustion exhaust gas.

[0132] When a fluidized bed type carbonation reaction tower is used as the carbonation reaction tower, in the formation of the fluidized bed, such as Figure 3 As shown, it is preferable to recover the kiln combustion exhaust gas discharged from the carbonation reaction tower and use it as fluidization gas. More specifically, it is preferable to use the kiln combustion exhaust gas for fluidized bed formation as follows: the kiln combustion exhaust gas after separating the carbonation unit powder from the kiln combustion exhaust gas containing carbonation unit powder discharged from the carbonation reaction tower by a dust collector, and the kiln combustion exhaust gas is drawn from the outlet of the carbonation unit induced draft fan that supplies the kiln combustion exhaust gas to the drying unit.

[0133] The temperature in the carbonation reaction tower is linked to the temperature of the kiln combustion exhaust supplied to the carbonation unit. Therefore, the temperature in the carbonation reaction tower can be adjusted by regulating the temperature of the kiln combustion exhaust supplied to the carbonation unit, specifically by the methods described in (i) to (iii) above.

[0134] The temperature in the carbonation reaction tower is preferably 250°C or higher, and preferably 600°C or lower as an upper limit. A temperature of 250°C or higher allows for efficient drying of cement raw materials, while a temperature below 600°C facilitates 100% carbonation efficiency of calcium oxide in the carbonation unit. To reduce power consumption by allowing for greater drying margins and stopping the drying unit based on raw material inventory, and to prevent malfunctions through maintenance and inspection during shutdown, a temperature of 300°C or higher is more preferable. Furthermore, to create a more economical cement firing equipment by using inexpensive rolled steel for the air ducts, a temperature of 400°C or lower is more preferable.

[0135] The temperature of the kiln combustion exhaust gas discharged from the carbonation reaction tower is linked to the supply temperature of the kiln combustion exhaust gas to the carbonation unit, and therefore cannot be generalized. However, since the carbonation reaction is exothermic, the temperature is higher than the supply temperature of the kiln combustion exhaust gas to the carbonation unit. Therefore, by using it to form a fluidized bed, the temperature inside the carbonation reaction tower can be maintained at a high temperature, thereby allowing the kiln combustion exhaust gas discharged from the carbonation unit to be appropriately used as a drying heat source for cement raw materials.

[0136] (Dust collector)

[0137] The carbonation unit preferably includes a dust collector that separates the carbonation-generated powder from the kiln combustion exhaust discharged from the carbonation reaction tower. By including a dust collector, the kiln combustion exhaust can be easily separated from the carbonation-generated powder.

[0138] As a dust collector, any conventional dust collector can be used, such as bag filters, electrostatic precipitators, inertial dust collectors, and other types of dust collectors.

[0139] (Pressure blower and induced draft fan)

[0140] The carbonation unit preferably includes a pressure blower and an induced draft fan. For example, such as Figure 3 As shown, it is preferable to have a fluidization pressurized blower for supplying the kiln combustion exhaust gas used to form the fluidized bed to the carbonation reaction tower. By having a fluidization pressurized blower, it is easy to maintain the fluidized bed formed by the kiln combustion exhaust gas in a good condition.

[0141] Furthermore, it is also preferable to have a carbonation unit induced draft fan for discharging kiln combustion exhaust from the dust collector and supplying it to the drying unit.

[0142] (Airflow adjustment baffle)

[0143] In the exhaust duct of the kiln combustion unit of the carbonation plant, baffles for air volume regulation can be provided as needed. For example, Figure 3 As shown, flow rate regulating baffles can be installed on the kiln combustion exhaust duct 6, the carbonation unit air supply duct 7, the carbonation unit exhaust duct 14, the inlet duct of the carbonation unit induced draft fan, and the inlet duct of the fluidization pressurized blower. By installing these flow rate regulating baffles, the flow rate of the kiln combustion exhaust can be adjusted, for example, the flow rate of the kiln combustion exhaust supplied to the carbonation unit, the flow rate of the kiln combustion exhaust supplied directly to the drying unit without supplying to the carbonation unit, and the flow rate of the kiln combustion exhaust used to form a fluidized bed. Furthermore, the pressure of the kiln combustion exhaust can also be adjusted.

[0144] As a baffle used for air volume regulation, there are no particular restrictions as long as it can regulate the flow rate of kiln combustion exhaust. For example, it can be appropriately selected from various baffles such as louver type, butterfly type, and blade control type.

[0145] (Carbon dioxide concentration meter)

[0146] The carbonation apparatus preferably includes a carbon dioxide concentration meter. For example, it is preferable to install the carbon dioxide concentration meter on the exhaust duct 14 of the carbonation apparatus.

[0147] By installing a carbon dioxide concentration meter on the exhaust duct 14 of the carbonation unit, the progress of the carbonation reaction in the carbonation tower can be monitored. Therefore, adjustments such as the amount of calcium oxide-containing powder to be added can be easily made based on the concentration of carbon dioxide in the kiln combustion exhaust gas discharged from the carbonation unit. As a result, carbon dioxide emissions into the atmosphere can be suppressed more efficiently, and efficient drying of cement raw materials can be achieved.

[0148] (Utilization of powder generated by carbonation unit)

[0149] The calcium carbonate-containing powder (carbonation unit-generated powder) produced by the carbonation reaction of a calcium oxide-containing powder in a carbonation unit contains, in addition to calcium carbonate, a cement raw material composition including silica, alumina, and iron oxide, and is therefore preferred for use as a cement raw material. Therefore, as... Figure 1 and Figure 3 As shown, the cement firing equipment of this embodiment preferably includes a carbonation device powder conveying device 15, which causes the calcium carbonate-containing powder generated in the carbonation device to be combined into a powder material supply device 16 that supplies the powder raw materials discharged from the drying and pulverizing device to the suspension preheater.

[0150] The calcium carbonate-containing powder (generated from the carbonation unit) is fed to the suspension preheater 1 by merging with the powder raw material discharged from the drying and pulverizing unit, and then to the rotary kiln. The calcium carbonate-containing powder (generated from the carbonation unit) then undergoes a decarbonation reaction, releasing carbon dioxide into the combustion exhaust (calciner combustion exhaust and kiln combustion exhaust).

[0151] In the cement calcining equipment of this embodiment, approximately 20% of the carbon dioxide generated from the decarbonation reaction of calcium carbonate-containing powder (powder generated in the carbonation unit) is emitted into the kiln combustion exhaust, and the remaining approximately 80% is emitted into the calcining furnace combustion exhaust. By reducing the carbon dioxide content in the kiln combustion exhaust in the carbonation unit and then releasing it into the atmosphere after utilizing it in the drying of cement raw materials, the amount of carbon dioxide emitted into the atmosphere can be reduced. Furthermore, by using the carbon dioxide-adsorbed powder in the carbonation unit as cement raw material, a portion of the carbon dioxide adsorbed in the powder can be emitted into the calcining furnace combustion exhaust. This increases the amount of carbon dioxide in the calcining furnace combustion exhaust, thereby improving the recovery rate of the carbon dioxide recovery device.

[0152] Furthermore, the carbonation unit, which emits carbon dioxide during calcination in the duct of the calcining furnace system, generates powder, which is then calcined in a rotary kiln to form part of the cement clinker, or separated by the separating device 12 and supplied to the carbonation unit as calcium oxide-containing powder via the first powder supply device 13, thereby being reused in the carbonation unit.

[0153] Furthermore, the calcium carbonate-containing powder (the powder generated by the carbonation unit) can be effectively used not only as part of the aforementioned cement raw materials, but also as fillers (mixing agents) contained in asphalt mixtures.

[0154] [Carbon Dioxide Recovery Unit]

[0155] The cement calcining equipment of this embodiment includes: a carbon dioxide recovery device that recovers carbon dioxide contained in the combustion exhaust gas discharged from the suspension preheater; and a calciner combustion exhaust gas discharge duct 5 for supplying the calciner combustion exhaust gas discharged from the calciner combustion exhaust gas outlet to the carbon dioxide recovery device. That is, in the cement calcining equipment of this embodiment, the combustion exhaust gas supplied to the carbon dioxide recovery device must be at least calciner combustion exhaust gas. As mentioned above, the calciner combustion exhaust gas contains more carbon dioxide than the kiln combustion exhaust gas, therefore recovering carbon dioxide from the calciner combustion exhaust gas helps to improve the carbon dioxide recovery efficiency. Furthermore, by using the carbon dioxide in the kiln combustion exhaust gas recovered as powder generated in the carbonation unit as cement raw material, the carbon dioxide content in the calciner combustion exhaust gas can be increased. Therefore, supplying the calciner combustion exhaust gas to the carbon dioxide recovery device and recovering carbon dioxide is effective.

[0156] Furthermore, the cement firing equipment of this embodiment may include a kiln combustion exhaust duct (not shown) for supplying kiln combustion exhaust to a carbon dioxide recovery device.

[0157] There are no particular restrictions on the form of carbon dioxide recovery equipment, as long as it can recover carbon dioxide from combustion exhaust. For example, it can be appropriately selected from liquid absorption, membrane separation, solid adsorption, compression liquefaction recovery and other methods.

[0158] The carbon dioxide recovered by the carbon dioxide recovery device can be effectively utilized, for example, through underground burial or methanation. This helps to reduce the emission of carbon dioxide from combustion exhaust gases, such as those from calcining furnaces, into the atmosphere.

[0159] [Drying and pulverizing equipment]

[0160] The cement calcining equipment of this embodiment includes a drying and pulverizing device for drying and pulverizing cement raw materials to produce powdered raw materials. As described above, the heat source for drying the cement raw materials is the exhaust gas from the kiln combustion unit.

[0161] Examples of drying and pulverizing devices that dry and pulverize cement raw materials to produce powdered raw materials include drying and pulverizing devices that combine drying devices such as rotary dryers and pulverizing devices such as tube mills, as well as drying and pulverizing devices such as vertical roller mills that can perform drying and pulverizing simultaneously.

[0162] [Cement raw material preparation]

[0163] The cement firing equipment of this embodiment preferably further includes: a powder raw material mixture collection device 17, which collects the powder raw material mixture; a chemical composition measuring device 18, which measures the chemical composition of the powder raw material mixture collected by the powder raw material mixture collection device; and a cement raw material blending device, which adjusts the proportion of the cement raw materials according to the measurement results of the chemical composition measuring device.

[0164] (Powder raw material mixture collection device, chemical composition determination device)

[0165] In the cement firing equipment of this embodiment, it is preferable to use a mixture of powder material generated from the carbonation unit (containing calcium carbonate) and powder material discharged from the drying and pulverizing unit, in addition to the aforementioned cement raw materials, as cement raw material. At this time, it is necessary to consider the chemical composition of the powder material generated from the carbonation unit (containing calcium carbonate) when preparing the cement raw material. With these devices, when using the calcium carbonate-containing powder material from the carbonation unit as cement raw material, the chemical composition of the mixture of powder material including the powder material discharged from the drying and pulverizing unit and the calcium carbonate-containing powder material from the carbonation unit can be quickly determined. Furthermore, by feeding this chemical composition back to the cement raw material preparation device, the chemical composition of the powder raw material supplied to the suspension preheater 1 can be quickly adjusted to the target value.

[0166] There are no particular limitations on the form of the aforementioned sampling and measuring devices. For example, various samplers such as trough samplers, spiral samplers, and Vezin samplers can be used for sampling. Various measuring devices such as fluorescence X-ray analyzers, ICP emission spectrophotometers, and atomic absorption spectrophotometers can be used for chemical composition determination.

[0167] Furthermore, adjustments to cement raw materials can be made using automatic control.

[0168] (Cement raw material blending device)

[0169] The cement firing equipment of this embodiment preferably includes a cement raw material mixing device, which is used to adjust the powder raw material supplied to the suspension preheater to the target chemical composition according to the chemical composition of the powder raw material supplied to the suspension preheater as determined by the chemical composition measuring device.

[0170] In a cement raw material blending device, the following methods can be used: when adjusting the calcium content in the cement raw materials, the supply of calcium (Ca) raw materials such as limestone can be increased or decreased; when adjusting the silicon content, the supply of silicon (Si) raw materials such as silica can be increased or decreased; when adjusting the aluminum content, the supply of aluminum (Al) raw materials such as fly ash can be increased or decreased; and when adjusting the iron content, the supply of iron (Fe) raw materials such as copper slag can be increased or decreased. This allows the chemical composition of the clinker to reach the target value.

[0171] More specifically, this can be achieved by adjusting the calcium content in cement raw materials by increasing or decreasing the supply of Ca raw materials such as limestone; adjusting the silicon content by increasing or decreasing the supply of Si raw materials such as silica; adjusting the aluminum content by increasing or decreasing the supply of Al raw materials such as fly ash; and adjusting the iron content by increasing or decreasing the supply of Fe raw materials such as copper slag.

[0172] Furthermore, the powder supply and conveying devices of the second powder supply device 10, the first powder supply device 13, the carbonation device-generated powder conveying device 15, and the powder raw material supply device 16 described above may be equipped with equipment for supplying and conveying powder as needed. Examples of such equipment for supplying and conveying include screw conveyors, plate feeders, and other conveying equipment.

[0173] (Regarding other equipment)

[0174] The structure and various conditions of the suspension preheater, the structure and various conditions of the carbonation unit, the structure and various conditions of the carbon dioxide recovery unit, and the structure and various conditions of the drying and pulverizing unit of the cement firing equipment of this embodiment have been described above. In addition to these devices, the cement firing equipment of this embodiment also includes a rotary kiln and a clinker cooler as main components.

[0175] A rotary kiln is a device for producing cement clinker by firing the preheated and calcined powdered raw materials in a suspension preheater 1. More specifically, it is a device for producing cement clinker by completely decarbonating the calcium carbonate contained in the powdered raw materials to produce calcium oxide, and then firing it at a high temperature of about 1450°C. Furthermore, a clinker cooler is a device used to cool the clinker generated in the rotary kiln.

[0176] These rotary kilns and clinker coolers can utilize conventionally used devices without limitation.

[0177] [Methods for manufacturing cement clinker]

[0178] The method for manufacturing cement clinker in this embodiment is as follows:

[0179] A manufacturing method that uses the cement firing equipment of this embodiment described above and adjusts it by any one of the following adjustment methods (i) to (iii).

[0180] (i) Adjust the supply rate of powdered raw materials to the suspension preheater;

[0181] (ii) Adjust the fuel supply to the rotary kiln;

[0182] (iii) Adjust the water spray volume into the combustion exhaust duct of the rotary kiln.

[0183] The cement firing equipment used in the cement clinker manufacturing method of this embodiment is the cement firing equipment described above. The cement firing equipment of this embodiment has been explained above.

[0184] Furthermore, regarding the adjustment methods described in (i) to (iii) above, in the manufacturing method of this embodiment, one of the adjustment methods described in (i) to (iii) above can be used, or multiple adjustment methods can be combined. Considering the ease of adjustment, it is preferable to combine multiple adjustment methods described in (i) to (iii) above.

[0185] In the cement clinker manufacturing method of this embodiment, it is preferable to use any of the adjustment methods (i) to (iii) above to adjust the temperature of the kiln combustion exhaust to 250°C or more and 600°C or less.

[0186] Regarding adjusting the temperature of the kiln combustion exhaust gas discharged from the kiln combustion exhaust outlet to 250°C or higher and 600°C or lower, as explained in the cement firing equipment of this embodiment above, by setting it within the above temperature range, the cement raw materials can be dried well, and the reaction efficiency of the carbonation reaction of calcium oxide in the carbonation device can be easily increased to close to 100%. Furthermore, as explained in the cement firing equipment of this embodiment above, it is also preferable to set it to 300°C or higher and 400°C or lower.

[0187] Example

[0188] The invention will now be specifically described through examples, but the invention is not limited to these examples in any way.

[0189] (Example)

[0190] Use with Figure 1 The cement clinker equipment shown in the flowchart operates by feeding cement raw materials at a rate of 200 tons / hour. Here, the temperature of the kiln combustion exhaust at the kiln combustion exhaust outlet is adjusted to 380°C, and the kiln combustion exhaust discharged from the kiln combustion exhaust outlet (… Figure 4 The total amount of (Jg) supplied to the carbonation unit is the total amount of kiln combustion exhaust gas discharged from the carbonation unit. Figure 4 (kg) of the raw material is supplied to the drying unit for drying cement raw materials. Powdered raw materials (kg) separated from the separating unit and supplied to the carbonation unit will be... Figure 4 The amount of (F) in the carbon dioxide is adjusted so that the amount of carbon dioxide in the kiln combustion exhaust discharged from the carbonation unit is 10% of the amount of carbon dioxide in the kiln combustion exhaust supplied to the carbonation unit, and the calcium carbonate-containing powder material transported from the carbonation unit ( Figure 4 The total amount of (G) in the calciner is used as cement raw material. Furthermore, the calciner combustion exhaust gas (G) discharged from the calciner combustion exhaust outlet... Figure 4 The total amount of Mg in the solution is supplied to the carbon dioxide recovery unit.

[0191] When the cement firing equipment reached a stable operating state, measurements were taken. Figure 4 The following data are presented: powdered raw material (A) at the outlet of the drying and pulverizing device; a mixture of powdered raw material (A) and calcium carbonate-containing powder (G) conveyed from the carbonation device (B); powdered raw material (C) discharged from the cyclone dust collector at the bottom of the kiln system duct of the suspension preheater; powdered raw material (D) discharged from the cyclone dust collector at the bottom of the calcining furnace system duct; powdered raw material (E) supplied to the rotary kiln after being separated from powdered raw material (D) by the separating device; powdered raw material (F) separated from the separating device and supplied to the carbonation device; and the flow rate and calcium carbonate and calcium oxide content of the powdered raw material (G) conveyed from the carbonation device. Furthermore, the balance of calcium carbonate, calcium oxide, and carbon dioxide was calculated based on the flow rates of combustion exhaust gases ((Ig), (Jg), (Kg), (Lg), and (Mg)) such as kiln combustion exhaust and calcining furnace combustion exhaust, as well as the carbon dioxide concentration, fuel flow rate, and carbon content in these combustion exhaust gases. The results are shown in Table 1.

[0192] By using a carbonation unit, it was confirmed that the amount of carbon dioxide (Lg) contained in the kiln combustion exhaust and emitted into the atmosphere was 4 tons / h, and the amount of carbon dioxide (Mg) recovered in the carbon dioxide recovery unit was 111 tons / h.

[0193] The temperature of the kiln combustion exhaust, adjusted to 380°C at the kiln combustion exhaust outlet, decreases to 350°C at the inlet of the carbonation unit due to heat loss from the kiln combustion exhaust outlet duct. The temperature of the kiln combustion exhaust in the carbonation unit exhaust duct (the temperature before merging with the kiln combustion exhaust outlet duct) is 380°C, and it is raised by 30°C through the carbonation reaction (an exothermic reaction) in the carbonation unit. Using the total amount of kiln combustion exhaust, cement raw materials were dried in the drying and pulverizing unit, resulting in the drying of the required amount of cement raw materials. Furthermore, the temperature of the kiln combustion exhaust at the outlet of the drying unit is 180°C at this time.

[0194] (Comparative example)

[0195] In this embodiment, the cement calcining equipment was operated in the same manner as in the embodiment, except that powdered raw materials were not supplied to the carbonation unit. Once the cement calcining equipment reached a stable operating state, the same measurements as in the embodiment were performed, and the balance of calcium carbonate, calcium oxide, and carbon dioxide was calculated. The measurement field is shown in... Figure 5 The calculation results are shown in Table 1.

[0196] It was confirmed that if the carbonation unit is not used, the amount of carbon dioxide emitted into the atmosphere along with the kiln combustion exhaust is 37 tons / h, and the amount of carbon dioxide recovered in the carbon dioxide recovery unit is 78 tons / h.

[0197] [Table 1]

[0198]

[0199] * "Non-energy source CO2" refers to carbon dioxide produced from powdered raw materials, while "energy source" refers to carbon dioxide produced from fuels used in suspension preheaters and rotary kilns.

[0200] In the table above, the abbreviations for A through Mg are as follows.

[0201] • (A): Powder raw material at the outlet of the drying and pulverizing device

[0202] • (B): A mixture of powder raw material (A) and powder containing calcium carbonate (G) conveyed from the carbonation unit.

[0203] • (C): Powdered raw materials discharged from the cyclone dust collector K1 at the bottom of the kiln system duct of the suspension preheater.

[0204] • (Cg): Carbon dioxide generated in the cyclone dust collector K1 through the decarbonation of the powdered raw material supplied to K1.

[0205] • (D): Powdered raw materials discharged from the cyclone dust collector at the bottom of the calcining furnace system air duct.

[0206] • (Dg): Carbon dioxide from the calcining furnace, generated in the cyclone dust collector C1 through decarbonation of powdered raw material (C).

[0207] • (E): Powdered raw material (D) is separated from the powdered raw material (D) by the separating device and then fed to the rotary kiln.

[0208] • (F): Powdered raw material separated from the separating device and fed to the carbonation unit

[0209] • (G): Powder containing calcium carbonate conveyed from the carbonation unit

[0210] • (H): Powder produced in a rotary kiln through decarbonation of powdered raw material (E).

[0211] • (Hg): Carbon dioxide generated in the rotary kiln through the decarbonation of powdered raw material (E).

[0212] • (Ig): Kiln combustion exhaust gas discharged from the rotary kiln

[0213] • (Jg): Kiln combustion exhaust gas discharged from the kiln combustion exhaust outlet

[0214] • (Kg): Kiln combustion exhaust gas discharged from the carbonation unit

[0215] • (Lg): Kiln combustion exhaust gas discharged from the drying unit

[0216] • (Mg): Combustion exhaust gas from the calciner furnace.

[0217] Based on the results of the embodiments and comparative examples, it was confirmed that the amount of powder raw material input and the clinker production rate can be kept constant, while the carbon dioxide emission into the atmosphere (Lg) can be reduced from 37 ton / h to 4 ton / h; furthermore, the carbon dioxide recovery rate (Mg) in the carbon dioxide recovery equipment can be increased from 78 ton / h to 111 ton / h; and, cement raw materials can be dried. Based on the cement calcining equipment of this embodiment and the method for manufacturing cement clinker using the cement calcining equipment, it was confirmed that carbon dioxide emissions into the atmosphere can be suppressed, and efficient drying of cement raw materials is possible.

Claims

1. A cement firing device, comprising: Drying and pulverizing equipment, which dries and pulverizes cement raw materials to produce powdered raw materials; A suspension preheater is used to preheat and calcine the powder raw materials; A rotary kiln, which fires the preheated and calcined powdered raw materials to produce cement clinker; A cement clinker cooler for cooling the cement clinker; A carbon dioxide recovery device that recovers carbon dioxide contained in the combustion exhaust gas discharged from the suspension preheater; and A carbonation device that produces a powder containing calcium carbonate by reacting combustion exhaust gas discharged from the suspension preheater with a powder containing calcium oxide. The suspended preheater, serving as a preheater, has the following characteristics: A calcining furnace, which calcines the powdered raw material; Two distinct air ducts: a calciner system air duct through which the combustion exhaust gas from the calciner passes and a kiln system air duct through which the combustion exhaust gas from the rotary kiln passes. The combustion exhaust outlet of the calcining furnace, which discharges from the suspension preheater through the air duct of the calcining furnace system, contains the combustion exhaust gas from the calcining furnace that has preheated and calcined the powder raw materials; and The kiln combustion exhaust outlet is the kiln combustion exhaust that is discharged from the suspension preheater and passes through the kiln system air duct to preheat and calcine the powder raw materials; The cement firing equipment also includes: Exhaust duct, which includes: A combustion exhaust duct for the calcining furnace, used to supply the combustion exhaust from the calcining furnace, which is discharged from the combustion exhaust outlet of the calcining furnace, to the carbon dioxide recovery device; A kiln combustion exhaust duct for supplying the kiln combustion exhaust discharged from the kiln combustion exhaust outlet to the drying equipment of the drying and pulverizing apparatus; a carbonation unit gas supply duct for supplying the kiln combustion exhaust through the kiln combustion exhaust duct to the carbonation unit; and a carbonation unit exhaust duct for supplying the kiln combustion exhaust discharged from the carbonation unit to the kiln combustion exhaust duct. The separating device and the first powder supply device are used to separate the powder raw material after preheating and calcination from the suspension preheater, and the first powder supply device is used to supply the powder raw material separated by the separating device as a powder containing the calcium oxide to the carbonation device. as well as The system includes an exhaust device, a powder raw material separation device, and a second powder supply device. The exhaust device extracts the kiln combustion exhaust before the cyclone dust collector at the bottom of the kiln system duct supplied to the suspension preheater. The powder raw material separation device separates the powder raw material contained in the kiln combustion exhaust extracted by the exhaust device. The second powder supply device supplies the powder raw material separated by the powder raw material separation device as a powder containing the calcium oxide to the carbonation device.

2. The method for manufacturing cement clinker according to claim 1, wherein, The separating device is installed in the powder material conduit that supplies the powder raw material, which has been preheated and calcined by the suspension preheater, to the rotary kiln.

3. The cement firing equipment according to claim 1, further comprising: A powder raw material supply device that supplies the powder raw material discharged from the drying and pulverizing device to the suspension preheater; and a powder material conveying device generated by the carbonation device that merges the powder material containing the calcium carbonate generated by the carbonation device with the powder raw material discharged from the drying and pulverizing device.

4. The cement firing equipment according to claim 3, further comprising: A powder raw material mixture collection device for collecting a mixture of powder containing calcium carbonate conveyed by the powder conveying device generated by the carbonation device and powder raw materials discharged from the drying and pulverizing device; a chemical composition determination device for determining the chemical composition of the powder raw material mixture collected by the powder raw material mixture collection device; and a cement raw material blending device for adjusting the proportion of the cement raw materials according to the determination results of the chemical composition determination device.

5. The cement firing equipment according to claim 1, wherein, The carbonation device is a fluidized bed reactor.

6. A method for manufacturing cement clinker, comprising using the cement firing equipment of claim 1, and adjusting it by any one of the following adjustment methods (i) to (iii), (i) Adjust the supply rate of powdered raw materials to the suspension preheater; (ii) Adjust the fuel supply to the rotary kiln; (iii) Adjust the water spray volume into the combustion exhaust duct of the rotary kiln.

7. The method for manufacturing cement clinker according to claim 6, wherein, The adjustment method described above adjusts the temperature of the kiln combustion exhaust gas discharged from the kiln combustion exhaust outlet to above 250°C and below 600°C.

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