Cement production system

Abstract

To provide a cement production system which makes it possible to reduce energy necessary for recovering carbon dioxide in a carbon dioxide separation and recovery apparatus.SOLUTION: A cement production apparatus 10 comprises a cement firing device 30 that calcines a cement raw material powder P, and a cement raw material powder producing device 40 to which an exhaust gas G generated by the calcination is supplied and which produces the cement raw material powder P from a cement raw material M. A carbon dioxide separation and recovery apparatus 20 comprises an absorption tower 21 in which an absorption liquid L that absorbs carbon dioxide from the exhaust gas G is stored, and a regeneration tower 22 that heats the absorption liquid L having absorbed carbon dioxide in the absorption tower 21 to separate carbon dioxide gas. The carbon dioxide gas G2 separated in the regeneration tower 22 is supplied to a predetermined part of the cement production apparatus 10 so that the concentration of carbon dioxide in the exhaust gas G discharged from the cement raw material powder producing device 40 and supplied to the absorption tower 21 becomes a concentration within a predetermined range corresponding to a type of the absorption liquid L stored in the absorption tower 21.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a cement production system equipped with a carbon dioxide separation and capture facility. [Background technology]

[0002] There are several technologies for capturing carbon dioxide (CO2), a greenhouse gas, including chemical absorption (amine method), physical absorption, cryogenic separation, and chemical looping. Chemical absorption is a carbon dioxide separation and capture technology that utilizes the carbon dioxide absorption and desorption properties of amine-based absorbents, and is suitable for large-volume, low-pressure gases compared to other methods, making it ideal for capturing carbon dioxide from exhaust gases emitted from existing cement manufacturing facilities.

[0003] Chemical absorption is capable of separating and capturing carbon dioxide with high efficiency, but requires a large amount of energy to capture carbon dioxide, with the theoretical energy required for capture being 2.0 GJ / t-CO2.

[0004] Therefore, in order to reduce the energy required to capture carbon dioxide, efforts have been made to improve the performance of amine-based absorption solutions, increase the heat exchange efficiency of carbon dioxide separation and capture equipment, and make effective use of exhaust heat, etc. (see, for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-6275 [Patent Document 2] Japanese Patent Publication No. 2022-7797 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in addition to the above-mentioned conventional techniques, it is desired to further reduce the energy required to capture carbon dioxide in a carbon dioxide separation and capture facility.

[0007] An object of the present invention is to provide a cement production system that can reduce the energy required to capture carbon dioxide in a carbon dioxide separation and capture facility. [Means for solving the problem]

[0008] The cement production system of the present invention is a cement production system comprising: a cement production facility having a cement calcination device that calcines cement raw powder; and a cement raw powder production device that is supplied with exhaust gas generated by the calcination and produces the cement raw powder from cement raw materials; and carbon dioxide separation and capture equipment having an absorption tower that stores an absorbing liquid that absorbs carbon dioxide from the exhaust gas; and a regeneration tower that heats the absorbing liquid that has absorbed carbon dioxide in the absorption tower to separate the carbon dioxide gas, wherein the carbon dioxide gas separated in the regeneration tower is supplied to a predetermined location in the cement production facility so that the carbon dioxide concentration in the exhaust gas discharged from the cement raw powder production device and supplied to the absorption tower falls within a predetermined concentration range that corresponds to the type of the absorbing liquid stored in the absorption tower.

[0009] The inventors of the present invention have found that there exists a range of carbon dioxide concentration in flue gas that is suitable for suppressing the energy required to capture carbon dioxide, depending on the type of absorption liquid stored in the absorption tower. In particular, if the carbon dioxide concentration is too low, the energy required to capture carbon dioxide becomes excessively large. However, the carbon dioxide concentration in the flue gas discharged from a cement manufacturing facility and supplied to an absorption tower varies greatly depending on the operating conditions of each part of the cement manufacturing facility, the composition of the cement raw materials, etc.

[0010] According to the cement production system of the present invention, the carbon dioxide gas separated in the regeneration tower is supplied to a predetermined location in the cement production facility so that the carbon dioxide concentration in the exhaust gas supplied to the absorption tower falls within a predetermined range according to the type of absorption liquid stored in the absorption tower. As a result, by setting the predetermined concentration range as a concentration range suitable for reducing the energy required to capture carbon dioxide, it is possible to reduce the energy required to capture carbon dioxide.

[0011] In the cement production system of the present invention, it is preferable that the carbon dioxide gas separated in the regeneration tower is supplied to the cement calcination apparatus together with the primary combustion air so that the ratio of carbon dioxide gas to the primary combustion air supplied to the cement calcination apparatus is within a predetermined range.

[0012] In this case, the ratio of carbon dioxide to the primary combustion air supplied to the cement burning equipment does not fall below a predetermined range, so excessive burning is prevented, and the overburning of cement and NO X Furthermore, since the ratio of carbon dioxide to the primary combustion air supplied to the cement calcination facility does not exceed a predetermined range, it is possible to prevent insufficient calcination.

[0013] When the temperature of the exhaust gas exceeds a predetermined range suitable for drying the cement raw material or cement raw material powder, it is necessary to cool the exhaust gas by spraying water or the like.

[0014] Therefore, in the cement production system of the present invention, it is preferable that the cement raw material powder generation apparatus has a raw material dryer that dries the cement raw material or the cement raw material powder obtained by pulverizing the cement raw material, and a first exhaust gas sensor that measures the temperature of the exhaust gas supplied to the cement raw material powder generation apparatus, and that the carbon dioxide gas separated in the regeneration tower is supplied to the raw material dryer together with the exhaust gas so that the temperature of the exhaust gas measured by the first exhaust gas sensor is within a predetermined temperature range suitable for drying the cement raw material or the cement raw material powder.

[0015] In this case, even if the temperature of the exhaust gas supplied to the raw material dryer is too high, it is possible to prevent excessive drying of the cement raw material and cement raw material powder without cooling by water spraying or the like.

[0016] Furthermore, in the cement manufacturing system of the present invention, it is preferable that the cement raw powder generating apparatus has a second exhaust gas sensor that measures the concentration of carbon dioxide in the exhaust gas discharged from the cement raw powder generating apparatus, and that the carbon dioxide gas separated in the regeneration tower is supplied together with the exhaust gas discharged from the cement raw powder generating apparatus so that the concentration of carbon dioxide in the exhaust gas measured by the second exhaust gas sensor falls within a predetermined range according to the type of the absorption liquid stored in the absorption tower.

[0017] In this case, the second exhaust gas sensor can be used to measure the concentration of carbon dioxide in the exhaust gas discharged from the cement raw material powder production apparatus, making it possible to reliably introduce into the absorption tower exhaust gas whose carbon dioxide concentration falls within a predetermined range according to the type of absorption liquid stored in the absorption tower. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a schematic diagram of a cement manufacturing system 100 according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0019] A cement production system 100 according to an embodiment of the present invention will be described with reference to Fig. 1. The cement production system 100 comprises a cement production facility 10 to which a carbon dioxide separation and capture facility 20 is attached.

[0020] The cement manufacturing facility 10 produces cement from cement raw materials M, and is composed of a cement firing device 30 that fires cement raw material powder P, a cement raw material powder production device 40 that produces cement raw material powder P from the cement raw materials M and supplies it to the cement firing device 30, and an exhaust device 50 that discharges exhaust gas G emitted from the cement firing device 30 and the cement raw material powder production device 40.

[0021] The cement burning apparatus 30 is composed of a preheater 31, a calciner 32, a cement kiln 33, and the like.

[0022] Preheater 31 is a preheater consisting of a multi-stage (here, four-stage) arrangement of cyclones 31a to 31d. Cement raw material powder P is supplied from cement raw material powder generating device 40 to the top-stage cyclone 31a, preheated as it moves sequentially downward through cyclones 31a to 31c, supplied from cyclone 31c to calciner 32, and finally supplied to cyclone 31d. Preheater 31 preheats cement raw material powder P by heat exchange with high-temperature exhaust gas G that is sucked up by induced draft fan 45 and rises.

[0023] The calciner 32 is provided below the preheater 31 and is equipped with a burner and the like. The type of the calciner 32 is not limited, and may be, for example, a fluidized bed type, a fluidized bed type, a spouted bed type, etc. Note that the calciner 32 may be omitted, and the cement raw material powder P may be supplied directly from the preheater 31 to the cement kiln 33.

[0024] The cement kiln 33 is equipped with a burner 33a, and burns the cement raw material powder P calcined in the calciner 32 at 1350°C to 1450°C to produce cement clinker C. The type of the cement kiln 33 is not limited, but may be, for example, a rotary type.

[0025] Air E as primary combustion air is supplied to the cement kiln 33 from outside by an induced draft fan 34 through a primary combustion air supply passage 35. A combustion sensor 36 that measures the concentrations of various components in the exhaust gas G discharged from the cement kiln 33 is provided at the outlet side of the cement kiln 33 or the inlet of the calciner 32. The combustion intensity of the burner 33a, the suction strength of the induced draft fan 34, and the like are controlled so that the concentrations measured by this combustion sensor 36 fall within the concentration range expected when good burning is performed in the cement kiln 33.

[0026] The cement clinker C obtained in the cement kiln 33 drops from a discharge port and is fed into a clinker cooler 37, where it is cooled to about 100° C. The cooled cement clinker C is taken out from an outlet of the clinker cooler 37 to the outside.

[0027] A portion of the exhaust gas G, which has been heated to a high temperature by cooling the cement clinker C in the clinker cooler 37, flows into the calciner 32. On the other hand, the exhaust gas G on the low-temperature side of the clinker cooler 37 passes through dust collection means such as an electric dust collector 51, is drawn to the chimney side by an exhaust fan 52, and is released into the atmosphere from a chimney 53.

[0028] The cement raw material powder generating device 40 is composed of a raw material dryer 41, a stabilizer 42, a raw material crusher 43, and the like.

[0029] The raw material dryer 41 is a dryer that dries the cement raw materials M supplied from a raw material tank 44 or the like. The cement raw materials M are, for example, limestone, clay, silica stone, iron slag, coal ash, sludge, clays, etc. The raw material dryer 41 is supplied with exhaust gas G discharged from the preheater 31 and drawn by an induced draft fan 45, and dries the cement raw materials M using this exhaust gas G.

[0030] The stabilizer 42 is supplied with the exhaust gas G, adjusts the temperature and moisture content of the cement raw material M supplied from the raw material dryer 41, and separates fine dust from the exhaust gas G.

[0031] A first flue gas sensor 47 is provided in the flow path 46 upstream of the raw material dryer 41 and the stabilizer 42 to measure the temperature of the flue gas G flowing through the flow path 46. If the temperature of the flue gas G measured by this first flue gas sensor 47 exceeds a predetermined temperature, a sprinkler device 48 installed in the flow path 46 sprays water to cool the flue gas G. This prevents the flue gas G supplied to the raw material dryer 41 and the stabilizer 42 from becoming excessively hot, which would cause the cement raw materials M to dry out excessively.

[0032] The raw material pulverizer 43 pulverizes and mixes the cement raw materials M supplied from the stabilizer 42 to generate a cement raw material powder P. This cement raw material powder P is temporarily stored in a cement raw material powder tank 49, and then supplied to the preheater 31 via a transport means (not shown), such as a conveyor or a bucket elevator. The cement material powder P obtained by pulverizing and mixing the cement raw materials M supplied from the stabilizer 42 in the raw material pulverizer 43 may be dried in the raw material dryer 41.

[0033] The exhaust gas G discharged from the raw material dryer 41 and the stabilizer 42 passes through dust collecting means such as an electric dust collector 54, is drawn to the chimney side by an exhaust fan 55, and is released into the atmosphere from a chimney 56. The electric dust collectors 51 and 54, the exhaust fans 52 and 55, and the chimneys 53 and 56 constitute the exhaust device 50 described above.

[0034] A second exhaust gas sensor 58 that measures the concentration of carbon dioxide contained in the exhaust gas G flowing through the flow path 57 is provided in the flow path 57 between the electrostatic precipitator 54 and the exhaust fan 55. This second exhaust gas sensor 58 can measure the concentration of carbon dioxide in the exhaust gas G introduced from the cement production facility 10 to the carbon dioxide separation and capture facility 20.

[0035] The carbon dioxide separation and capture facility 20 is composed of an absorption tower 21, a regeneration tower 22, a heat exchanger 23, and the like.

[0036] Exhaust gas G containing carbon dioxide (CO2) is introduced into the absorption tower 21 from the cement production facility 10 by an induced draft fan 59. This exhaust gas G comes into gas-liquid contact with an absorbing liquid L in the absorption tower 21, and the carbon dioxide is absorbed by the absorbing liquid L. The absorbing liquid L is an amine-based absorbing liquid that absorbs carbon dioxide by a chemical absorption method, such as MEA, MDEA, AMP, or PZ / PIPA.

[0037] The absorbing liquid L that has absorbed carbon dioxide in the absorption tower 21 is sent to the heat exchanger 23 by the pump 24 , where it is heated and then supplied into the regeneration tower 22 .

[0038] This absorption liquid L is stored in the lower part of the regeneration tower 22 and heated by a heater 25 using a boiler, steam, or the like, to raise the temperature to 70°C to 110°C. As a result, the carbon dioxide in the absorption liquid L is released as carbon dioxide gas into the regeneration tower 22. This gas G2 containing carbon dioxide gas rises inside the regeneration tower 22 and is released via the carbon dioxide recovery pipe 26, and a part of it is stored in the storage tank 28 as gas G2 containing high-purity carbon dioxide gas.

[0039] On the other hand, the absorbent L from which carbon dioxide has been removed and regenerated is sent by the pump 27 to the heat exchanger 23, where it is cooled and then supplied from the top of the absorption tower 21, where it again absorbs carbon dioxide from the flue gas G.

[0040] The exhaust gas G3 from which carbon dioxide has been removed rises inside the absorption tower 21 and is discharged via the exhaust gas discharge pipe 29, for example, to the outside.

[0041] In the cement production system 100 described above, carbon dioxide is captured from exhaust gas G generated in the cement production facility 10 by the carbon dioxide separation and capture facility 20. In the carbon dioxide separation and capture facility 20, carbon dioxide can be captured with high efficiency by a chemical absorption method using an amine-based absorption solution L, but as described above, the theoretical recovery energy is 2.0 GJ / t-CO2, and the energy required to capture carbon dioxide is large.

[0042] Therefore, the inventors of the present invention sought ways to reduce the energy required to capture carbon dioxide, and discovered that the energy required to capture carbon dioxide varies depending on the concentration of carbon dioxide in the exhaust gas G that comes into contact with the absorption liquid L.

[0043] The carbon dioxide concentration suitable for suppressing this energy varies depending on the type of absorbent L. For example, when a monoethanolamine aqueous solution (30% by volume) is used as the absorbent L, the carbon dioxide concentration is preferably 10 to 30% by volume, and more preferably 15 to 25% by volume.

[0044] Therefore, each part of the cement production facility 10 may be operated so that the carbon dioxide concentration in the flue gas G introduced into the carbon dioxide separation and capture facility 20 falls within the above range. However, the carbon dioxide concentration in the flue gas G varies greatly depending on the operating conditions of each part of the cement production facility 10, the composition of the cement raw material M, etc.

[0045] Therefore, gas G2 containing high-purity carbon dioxide gas can be introduced from any point in the cement production facility 10 directly from the regeneration tower 22 or from the storage tank 28 so that the carbon dioxide concentration in the flue gas G introduced from the cement production facility 10 to the carbon dioxide separation and capture facility 20, as measured by the second flue gas sensor 58, falls within a predetermined range. This is because introducing gas G2 from any point in the cement production facility 10 increases the carbon dioxide concentration in the flue gas G introduced from the cement production facility 10 to the carbon dioxide separation and capture facility 20. For example, when 10% by volume of gas G2 containing 99% by volume of carbon dioxide is mixed with air E containing 21% by volume of oxygen and 79% by volume of nitrogen, the concentration of carbon dioxide contained in the primary combustion air is 9.9% by volume.

[0046] In this way, even if gas G2 is introduced from any location in the cement production facility 10, it is possible to reduce the energy required to capture carbon dioxide, but there is a risk of interfering with the operation of each part of the cement production facility 10. Therefore, it is preferable to introduce gas G2 from a location that does not interfere with the operation of each part of the cement production facility 10, and more preferably from a location that has a favorable effect.

[0047] Even if the carbon dioxide concentration exceeds the upper limit of the above-mentioned range, the energy required to capture the carbon dioxide does not increase significantly. Also, the concentration of carbon dioxide emitted from the cement production facility 10 rarely exceeds these upper limit values. Therefore, control may be performed so that the flue gas G having a carbon dioxide concentration equal to or higher than the lower limit of the above-mentioned range is introduced into the carbon dioxide separation and capture facility 20.

[0048] As the first point for introducing gas G2 into cement production equipment 10, it is preferable to introduce gas G2 from inlet A provided midway through primary combustion air supply path 35 via induced draft fan 61. Primary combustion air E supplied to burner 33a of cement kiln 33 flows through primary combustion air supply path 35, and gas G2 is mixed with primary combustion air E and supplied to burner 33a.

[0049] In this case, however, the gas G2 is introduced so that the ratio of carbon dioxide gas to the primary combustion air E does not exceed a predetermined value. This predetermined value may be determined so that good combustion is maintained in the burner 33a. Since the gas G2 is mixed with the primary combustion air E, excessive burning of the cement raw material powder P in the cement kiln 33 is prevented, and excessive burning of the cement and NO are prevented. X It is possible to suppress the occurrence of

[0050] Furthermore, an operator or a computer may determine the combustion state in the cement kiln 33 based on the concentrations of various components in the exhaust gas G measured by the combustion sensor 36, and adjust the proportion of the gas G2 to be mixed into the primary combustion air E. Furthermore, although not shown, the gas G2 may be mixed into the secondary combustion air supplied to the burner 33a.

[0051] As a second location, it is preferable to introduce gas G2 via induction fan 62 from inlet B provided in flow path 46 on the upstream side of raw material dryer 41 and stabilizer 42. Exhaust gas G supplied to raw material dryer 41 and stabilizer 42 flows through flow path 46, and gas G2 is mixed with exhaust gas G and supplied to raw material dryer 41 and stabilizer 42.

[0052] As a result, when the temperature of the exhaust gas G flowing through the flow path 46 measured by the first exhaust gas sensor 47 exceeds a predetermined temperature, the temperature of the exhaust gas G can be lowered by mixing in the gas G2, which is at about room temperature, and it becomes possible to prevent excessive drying of the cement raw materials M and the cement raw material powder P without cooling the exhaust gas G by, for example, spraying water. Note that even when the gas G2 is mixed with the exhaust gas G from the inlet B, the mixed gas may be cooled by spraying water using the sprinkler device 48. Furthermore, the inlet B may be provided either upstream or downstream of the first exhaust gas sensor 47.

[0053] As a third location, it is preferable to introduce gas G2 via an induced draft fan 64 from an inlet C provided in the middle of a flow path 63 extending from the outlet of the cement production facility 10 to the inlet of the carbon dioxide separation and capture facility 20. Exhaust gas G having a carbon dioxide concentration measured by the second flue gas sensor 58 flows through this flow path 63. This makes it possible to reliably ensure that the carbon dioxide concentration in the flue gas G introduced into the absorption tower 21 of the carbon dioxide separation and capture facility 20 falls within a predetermined range.

[0054] A second exhaust gas sensor 58 may be provided in the flow path 63. In this case, the inlet C may be provided either upstream or downstream of the second exhaust gas sensor 58. Also, an inlet C for the gas G2 may be provided in the flow path 63. In this case, however, a portion of the gas G2 may be discharged directly to the outside via the chimney 56.

[0055] Furthermore, there are the above-mentioned advantages when the gas G2 is introduced into the cement manufacturing equipment 10 from the inlet A or the inlet B. Therefore, it is preferable to introduce the gas G2 within the range that can be introduced from the inlet A and the inlet B, and then introduce the remaining gas G to be introduced from the inlet C.

[0056] The present invention is not limited to the cement production system 100 specifically described in the above embodiment, and can be modified as appropriate within the scope of the claims.

[0057] For example, in the above-described cement raw material powder generating apparatus 40, the raw material pulverizer 43 is disposed downstream of the raw material dryer 41 and the stabilizer 42. However, the raw material pulverizer 41 and the stabilizer 42 may be disposed downstream of the raw material pulverizer 43. [Explanation of symbols]

[0058] 10...Cement manufacturing equipment, 20...Carbon dioxide separation and capture equipment, 21...Absorption tower, 22...Regeneration tower, 23...Heat exchanger, 24...Pump, 25...Heater, 26...Carbon dioxide capture pipe, 27...Pump, 28...Storage tank, 29...Exhaust gas exhaust pipe, 30...Cement burning equipment, 31...Preheater, 32...Calminer, 33...Cement kiln, 33a...Burner, 34...Induced draft fan, 35...Primary combustion air supply path, 36...Combustion sensor, 37...Clinker cooler, 40...Cement raw material powder generating device, 41...Raw material dryer, 42...Stabilizer, 43...Raw material crusher, 44...Raw material tank, 45...Induced draft fan, 46...Flow path, 47...First exhaust gas sensor, 48...Sprinkler device, 49...Cement raw material powder tank, 50...exhaust device, 51,54...electrostatic precipitator, 52,55...exhaust fan, 53,56...chimney, 57...flow path, 58...second flue gas sensor, 59...induced draft fan, 61,62,64...induced draft fan, 63...flow path, 100...cement manufacturing system, A,B,C...inlet, E...primary combustion air, G...exhaust gas, G2...gas containing high-purity carbon dioxide, G3...exhaust gas from which carbon dioxide has been removed, L...absorption liquid, M...cement raw material, P...cement raw material powder.

Claims

1. A cement manufacturing facility including a cement calcination device that calcines cement raw material powder, and a cement raw material powder production device that is supplied with exhaust gas generated by the calcination and produces the cement raw material powder from the cement raw materials; A cement production system equipped with carbon dioxide separation and capture equipment including an absorption tower in which an absorption liquid that absorbs carbon dioxide from exhaust gas is stored, and a regeneration tower that heats the absorption liquid that has absorbed carbon dioxide in the absorption tower to separate carbon dioxide gas, a cement production system, characterized in that the carbon dioxide gas separated in the regeneration tower is supplied to a predetermined location in the cement production facility so that the carbon dioxide concentration in the exhaust gas discharged from the cement raw material powder production device and supplied to the absorption tower falls within a predetermined range according to the type of the absorption liquid stored in the absorption tower.

2. 2. The cement manufacturing system according to claim 1, wherein the carbon dioxide gas separated in the regeneration tower is supplied to the cement calcination apparatus together with the primary combustion air so that the ratio of the carbon dioxide gas to the primary combustion air supplied to the cement calcination apparatus is within a predetermined range.

3. the cement raw material powder generating apparatus includes a raw material dryer that dries the cement raw material or the cement raw material powder obtained by pulverizing the cement raw material, and a first exhaust gas sensor that measures a temperature of the exhaust gas supplied to the cement raw material powder generating apparatus, 2. The cement manufacturing system according to claim 1, wherein the carbon dioxide gas separated in the regeneration tower is supplied to the raw material dryer together with the exhaust gas so that the temperature of the exhaust gas measured by the first exhaust gas sensor falls within a predetermined temperature range suitable for drying the cement raw material or the cement raw material powder.

4. the cement raw powder generating apparatus has a second exhaust gas sensor that measures the concentration of carbon dioxide in the exhaust gas discharged from the cement raw powder generating apparatus, 2. The cement manufacturing system according to claim 1, wherein the carbon dioxide gas separated in the regeneration tower is supplied together with the exhaust gas discharged from the cement raw material powder generation device so that the carbon dioxide concentration in the exhaust gas measured by the second exhaust gas sensor falls within a predetermined range according to the type of the absorption liquid stored in the absorption tower.

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