Carbonization treatment equipment

Abstract

Provided is a carbonization treatment apparatus capable of efficiently performing a carbonization treatment. Provided is a carbonization treatment apparatus for subjecting a solid substance contained in a treatment object to a carbonization treatment by bringing the treatment object into contact with carbon dioxide while stirring the treatment object. The apparatus includes: a reaction vessel having an accommodation space in which a processing object is accommodated; at least one stirrer that rotates about a vertically extending axis to stir the processing object accommodated in the accommodation space; and the at least one stirrer is configured to move in a planetary motion in the accommodation space when the object to be processed is stirred.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a carbonization treatment apparatus and a carbonization treatment method. BACKGROUND

[0002] Conventionally, fly ash discharged from a waste incineration facility is sometimes subjected to carbonization treatment for the purpose of reducing pH or preventing elution of heavy metals. A known apparatus for such carbonization treatment is disclosed in the following Patent Literature 1, which includes a reaction vessel having a cylindrical main body with both ends closed, and provided with a central axis of the cylindrical main body extending in a horizontal direction, and an agitator having a rotational axis provided along the central axis of the reaction vessel.

[0003] The carbonization treatment in this type of apparatus includes circulating a gas containing carbon dioxide within the apparatus while agitating a treatment object in a paste or slurry form containing fly ash and water, thereby converting calcium oxide, calcium hydroxide, or the like into calcium carbonate.

[0004] LIST OF CITATIONS

[0005] PATENT LITERATURE

[0006] Patent Literature 1: JP 2002-224640 A SUMMARY

[0007] PROBLEMS TO BE SOLVED BY THE INVENTION

[0008] When using an agitator having a configuration in which an impeller is mounted to a rotational shaft passing through the center of a horizontal cylindrical reaction vessel as described in the above-mentioned patent literature, the rotational shaft can be sized to have a length close to the entire length of the reaction vessel, and the impeller can be provided at two or more positions along such a longitudinal axis. This configuration can suppress the occurrence of a portion in the apparatus where the treatment object is hardly agitated, and thus can enable carbon dioxide to be easily distributed over the entire treatment object.

[0009] However, the vertically rotating impeller of this type of apparatus can jump onto the treatment object. In the downstream stage of the carbonization treatment, fly ash and water are relatively uniformly mixed together in the treatment object, but the fly ash sometimes lumps in the pretreatment stage. Therefore, using an agitator including a vertically rotating impeller can cause the ash to easily fly upward inside the apparatus. Thus, the flown ash can be entrained by the gas to be discharged from the apparatus, and thus discharged to the outside of the apparatus. In the case where the fly ash intrudes into the gas discharge system, cleaning must be frequently performed, which hinders efficient operation.

[0010] To prevent the above problems, it is conceivable to use a stirrer having a stirring impeller mounted to a vertically extending rotation shaft, and to perform the carbonization treatment by horizontal rotation of the stirring impeller. However, sufficient stirring is hardly performed by the horizontal rotation of the stirring impeller alone. Because of this, it is difficult to effectively perform the carbonization treatment by this conventional method. Therefore, an object of the present disclosure is to provide a carbonization treatment apparatus and a carbonization treatment method capable of achieving effective carbonization treatment.

[0011] Solution to the problem

[0012] The present inventors have conducted intensive studies in order to solve the above problems, and have found that even if a stirring impeller that does not rotate vertically but horizontally is used, when the rotation of the stirring impeller is performed in a specific manner, carbon dioxide can be easily distributed over the entire treatment object, and furthermore, solid matter can be inhibited from being discharged from the reaction vessel, thereby completing the present disclosure.

[0013] To solve the above problems, the present disclosure provides a carbonization treatment apparatus for subjecting solid matter contained in a treatment object to carbonization treatment by contacting the treatment object with carbon dioxide while stirring the treatment object, the apparatus including: a reaction vessel having a housing space in which the treatment object is housed; at least one stirrer that rotates about a vertically extending axis to stir the treatment object housed in the housing space; and the at least one stirrer is configured to move in planetary motion in the housing space while the treatment object is stirred.

[0014] The present disclosure also provides a carbonization treatment method for subjecting solid matter to carbonization treatment by carbon dioxide using a carbonization treatment apparatus including: a reaction vessel having a housing space in which a treatment object containing the solid matter is housed; at least one stirrer that rotates about a vertically extending axis to stir the treatment object housed in the housing space; and the at least one stirrer is configured to move in planetary motion in the housing space; the method including: stirring the treatment object by the at least one stirrer, thereby performing the carbonization treatment. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 is a schematic view showing the configuration of an apparatus in a certain incineration facility.

[0016] Figure 2 is a schematic view showing one example of a carbonization treatment apparatus.

[0017] Figure 3 is a schematic view showing Figure 2 a partial enlarged view showing the appearance of a stirrer of the carbonization treatment apparatus of

[0018] Figure 4 is a schematic view showing a stirring region of the carbonization treatment apparatus, specifically, a cross-sectional view taken along a line IV-IV observed in the direction of the arrow in Figure 2

[0019] Figure 5A is a schematic view showing a stirring region of the carbonization treatment apparatus of Figure 2

[0020] Figure 5B is a schematic view showing a stirring region of the carbonization treatment apparatus of Figure 2

[0021] Figure 5C is a schematic view showing a stirring region of the carbonization treatment apparatus of Figure 2 DETAILED DESCRIPTION

[0022] Hereinafter, a method of subjecting fly ash to carbonization treatment using a carbonization treatment apparatus installed in an incineration facility according to one embodiment of the present disclosure will be described. According to the carbonization treatment apparatus of the present embodiment, fly ash is subjected to carbonization treatment by bringing a treatment object containing fly ash and water into contact with a gas containing carbon dioxide. Fly ash particles have a large specific surface area, and thus efficient carbonization treatment can be performed for fly ash itself, but fly ash can be agglomerated. Therefore, it is difficult to sufficiently stir fly ash by a conventional method. Further, fly ash can be entrained by the gas that has been used for carbonization treatment and discharged to the outside together with the gas. The treatment object subjected to the carbonization treatment of the present embodiment can be any carbonizable material, and is not limited to fly ash. The treatment object subjected to carbonization treatment by the carbonization treatment apparatus of the present embodiment is also not limited to particles.

[0023] To prevent fly ash from being discharged to the outside of the apparatus, a fine filter or the like can be installed. This can cause an increase in load of a blower or the like for supplying the apparatus with the gas containing carbon dioxide, which can also hinder efficient carbonization treatment. According to the present embodiment, even in the case where the object to be subjected to carbonization treatment is fine particles such as fly ash, good stirring can be performed while preventing fly ash from flying upward. Therefore, the present embodiment enables efficient carbonization treatment. This effect is not limited to the case where the object to be subjected to carbonization treatment is fly ash. In the case where the object to be subjected to carbonization treatment is a solid substance, the efficiency of carbonization treatment can be increased by breaking the solid substance into small pieces and thus increasing the specific surface area of the solid substance. However, such small pieces of the solid substance can be entrained by the gas to be discharged. Further, even in the case where the solid substance is in the form of large-sized agglomerates, the agglomerates collide with each other into small pieces, which can be entrained by the gas to be discharged.

[0024] ​​​​The treatment object subjected to the carbonization treatment by the carbonization treatment apparatus of the present embodiment is a solid substance. The solid substance to be subjected to the carbonization treatment can be a product resulting from a thermal treatment. Examples of the thermal treatment include a treatment that causes only melting without accompanying thermal decomposition and a treatment that causes thermal decomposition. Examples of the thermal decomposition include those performed for the purpose of incineration, combustion, gasification, or calcination. Examples of the object to be subjected to the thermal decomposition include municipal waste, biomass, papermaking sludge, sewage sludge, cement raw material, and iron raw material. The solid substance to be subjected to the carbonization treatment can be a product derived from these types of objects to be subjected to the thermal decomposition. Examples of the product resulting from the thermal decomposition include incineration ash. Examples of the incineration ash include main ash and fly ash. The incineration ash to be subjected to the carbonization treatment can be in the form of molten slag. The product resulting from the thermal decomposition can be a slag generated during a metal refining process.

[0025] Figure 1 A facility that produces carbonizable material in the form of an incineration facility 100 including an incinerator 10 is shown. The incinerator 10 incinerates an incineration object such as waste and emits a high-temperature exhaust gas.

[0026] In addition to containing a gas such as carbon dioxide, oxidized sulfur, nitric oxide, or hydrogen chloride, the exhaust gas emitted from the incinerator 10 also contains fly ash as a solid substance. The fly ash generally includes a component derived from an alkaline agent in addition to a component derived from the incineration object. The fly ash generally contains at least one chemical compound selected from the group consisting of potassium, calcium, and magnesium. The fly ash to be subjected to the carbonization treatment in the present embodiment by the carbonization treatment apparatus and the carbonization treatment method can contain at least one chemical compound selected from the group consisting of, for example, sulfur, phosphorus, and silicon. The fly ash can include at least one selected from the group consisting of sodium, zinc, iron, aluminum, copper, and compounds thereof. The fly ash can also contain heavy metals such as lead or hexavalent chromium or compounds thereof.

[0027] Examples of the compound include oxides, hydroxides, carbides, carbonates, carbohydrates, nitrides, nitric substances, sulfides, sulfated substances, halides, and the like. The carbonization treatment apparatus 50 in the present embodiment functions to suppress elution of heavy metals when the fly ash is subjected to the carbonization treatment and the fly ash after the carbonization treatment is buried in the ground or the like. In some examples, the fly ash in which the amount of elution of lead is 0.3 mg / L or more is subjected to the carbonization treatment. In some examples, the fly ash in which the amount of elution of hexavalent chromium is 1.5 mg / L or more is subjected to the carbonization treatment.

[0028] The carbonization treatment method can be executed for any application, and there is no limitation on facilities in which the method is used. For example, the method can be executed in an incineration facility 100. The incineration facility 100 of the present embodiment includes: an incinerator 10; a cooling tower 20 for cooling exhaust gas discharged from the incinerator 10; an alkaline treatment device 30 for adding an alkaline agent, such as slaked lime, to the exhaust gas so as to neutralize an acidic gas contained in the exhaust gas that has been cooled in the cooling tower 20; a fly ash removal device 40 equipped with a bag filter for removing fly ash as a solid content from the exhaust gas to which the alkaline agent has been added in the alkaline treatment device 30; and a carbonization treatment apparatus 50 for subjecting the fly ash that has been removed by the fly ash removal device 40 to carbonization treatment. The carbonization treatment apparatus 50 of the present embodiment is configured so that a clay-like treatment object X can be prepared by adding water to the contained fly ash, and the treatment object X can be subjected to carbonization treatment while the treatment object X is stirred, as will be described later.

[0029] The incineration facility 100 is configured to be able to use carbon dioxide contained in the exhaust gas, in which the fly ash has been removed by the fly ash removal device 40 by passing the fly ash through the fly ash removal device 40, for carbonization treatment in the carbonization treatment apparatus 50. More specifically, according to the configuration of the incineration facility 100 of the present embodiment, the exhaust gas that has passed through the fly ash removal device 40 is partially or entirely brought into contact with water in a water contact device 60 equipped with a scrubber, to remove a soluble gas by the water contact device 60, so that the exhaust gas with the soluble gas removed can be supplied to the carbonization treatment apparatus 50. Components, such as hydrogen chloride, sulfur dioxide, or nitrogen dioxide, which can be more easily removed from the exhaust gas by contact with water than carbon dioxide, can be removed in the water contact device 60. In the present embodiment, the exhaust gas is supplied to the carbonization treatment apparatus 50 as a gas containing carbon dioxide, but the gas is not limited to the exhaust gas, and various gases can be used. For example, carbon dioxide gas having a purity of ≥ 99 mass% can be supplied to the carbonization treatment apparatus 50, which is filled in a cylindrical member and is commercially available.

[0030] Carbon dioxide for carbonization treatment in the carbonization treatment apparatus 50 can be introduced into the carbonization treatment apparatus 50 in a liquid form or a solid form. Liquidized carbon dioxide or carbonated water can be used for carbonization treatment. Dry ice can be used for carbonization treatment. A liquid or a solid from which carbon dioxide is generated by thermal decomposition or a chemical reaction (for example, sodium bicarbonate, sodium carbonate) can be used for carbonization treatment. Carbonization treatment can be executed by using high-purity carbon dioxide gas or dry ice even in a case where the water contact device 60, the later-described air blower 70, the later-described dehumidifying device 80, the later-described cooling device 90, and the like are not utilized. Carbonization treatment can be executed without utilizing these devices even in a case where the exhaust gas is used.

[0031] In the incineration facility 100 of the present embodiment, the exhaust gas line LE, which is a passage for discharging exhaust gas from the fly ash removal device 40, is branched into an exhaust gas discharge line LE1 for discharging exhaust gas to the outside of the system and an exhaust gas supply line LE2 for supplying exhaust gas to the carbonization treatment apparatus 50. In the incineration facility 100 of the present embodiment, a valve V1 is installed at the branching point of the exhaust gas line LE to be able to switch the passage of exhaust gas between the exhaust gas discharge line LE1 and the exhaust gas supply line LE2 and adjust the amount of exhaust gas to be supplied to the carbonization treatment apparatus 50.

[0032] In the incineration facility 100 of the present embodiment, the exhaust gas supply line LE2 includes the water contact device 60 and the blower 70 and is configured so that back pressure can be applied to the exhaust gas supplied to the carbonization treatment apparatus 50. In the incineration facility 100 of the present embodiment, the exhaust gas supply line LE2 includes a dehumidification device 80, such as a mist separator, to be able to reduce moisture contained in the exhaust gas supplied to the carbonization treatment apparatus 50.

[0033] According to some examples of the present disclosure, the incineration facility 100 of the present embodiment further includes a cooling device 90 for cooling the inner wall surface of the carbonization treatment apparatus 50 that comes into contact with the treatment object X. The cooling device 90 is configured to be able to: circulate a cooling liquid between itself and the carbonization treatment apparatus 50; cool the cooling liquid that has been heated in the carbonization treatment apparatus 50 to have a lower temperature; and thereafter supply the cooling liquid again to the carbonization treatment facility 50.

[0034] The carbonization treatment apparatus 50 includes: a reaction vessel 51 having a housing space 51a for housing a treatment object containing fly ash and water; at least one agitator 52 that rotates within the housing space 51a around a vertically extending axis to agitate the treatment object X housed in the housing space 51a; and a scraper 53 for scraping off the treatment object X adhering to the inner wall surface of the reaction vessel 51. In the carbonization treatment apparatus 50 of the present embodiment, the agitator 52 is configured to move in planetary motion in the housing space 51a while the treatment object X is being agitated.

[0035] The expression “the agitator 52 is configured to move in planetary motion” means that the agitator 52 has a rotation axis parallel to the vertically extending central axis and is able to move on a circular path around the central axis.

[0036] The reaction container 51 includes a material supply member 510 through which fly ash and water can be introduced into the accommodation space 51a. The material supply member 510 includes a through-hole (hereinafter also referred to as a material supply hole 510h) that extends through a wall of the reaction container 51 to provide communication between the accommodation space 51a and an external space, and a lid 510p that opens and closes the through-hole (i.e., the material supply hole 510h).

[0037] The reaction container 51 includes a gas intake member 511 for sucking a gas containing carbon dioxide (i.e., an exhaust gas that has passed through the water contact device 60) into the accommodation space 51a so as to subject fly ash contained in the treatment object X to a carbonization treatment while the treatment object X is stirred by the stirrer 52, and a gas discharge member 512 for discharging a gas that has been sucked into the accommodation space 51a from the gas intake member 511 and used for the carbonization treatment from the accommodation space 51a. The gas discharge member 512 of the present embodiment is configured to be able to discharge a gas of an upper end region of the accommodation space 51a.

[0038] In the case where a high-purity carbon gas or dry ice is used for the carbonization treatment, a reaction container that does not have a gas intake member 511 or a gas discharge member can be used.

[0039] The reaction container 51 of the present embodiment has a low-profile, hollow cylindrical shape that has a larger dimension in the horizontal direction than in the vertical direction. That is, the accommodation space 51a of the reaction container 51 has a cylindrical shape. The reaction container 51 has a circumferential side wall 51s that has a cylindrical shape defining a side surface of the accommodation space 51a, a bottom wall 51b that has a circular plate shape defining a bottom of the accommodation space 51a, and a top wall 51c that has a circular plate shape defining a top of the accommodation space 51a.

[0040] In the reaction container 51, the material supply hole 510h is provided to extend through the top wall 51c. The gas intake member 511 has a through-hole (hereinafter also referred to as a gas intake hole 511h) that extends through the top wall 51c in the same manner as the material supply member 510. The gas discharge member 512 also has a through-hole (hereinafter also referred to as a gas discharge hole 512h) that extends through the top wall 51c in the same manner as the gas intake member 511. The gas discharge member 512 opens to an inner wall surface 51cs of the top wall 51c so that a gas of an upper end region of the accommodation space 51a can be discharged through the gas discharge member 512. The gas intake hole 511h and the gas discharge hole 512h are disposed opposite to each other with respect to a center axis of the accommodation space 51a at a large distance from each other in the horizontal direction.

[0041] In the reaction container 51, the circumferential side wall 51s and the bottom wall 51b are integrally formed with each other while being formed separately from the top wall 51c. The top wall 51c is detachably attached to the circumferential side wall 51s and can be fitted to an upper end opening of the circumferential side wall 51s of a cylindrical shape. The accommodation space 51a of the reaction container 51 is configured as a closed space with the top wall 51c and the circumferential side wall 51s being fitted together without a gap therebetween, so that the accommodation space 51a can be made into a positive pressure state (i.e., a pressurized state) or a negative pressure state (i.e., a depressurized state) by adjusting the amount of gas to be sucked from the gas inlet hole 511h or the amount of gas to be discharged from the gas outlet hole 512h.

[0042] The circumferential side wall 51s is configured to allow at least the lower side of the inner wall surface 51ss to be cooled by a cooling liquid supplied from the cooling device 90 and has a flow runner 51r through which the cooling liquid is circulated. The reaction container 51 can be configured to be able to cool not only the inner wall surface 51ss of the circumferential side wall 51s but also the inner wall surface 51bs of the bottom wall 51b.

[0043] In the illustrated embodiment, the carbonization treatment apparatus 50 includes a plurality of agitators 52 to agitate the treatment object X accommodated in the reaction container 51. The plurality of agitators 52 includes a first agitator 521 and a second agitator 522. In the present embodiment, the second agitator 522 can be rotated faster than the first agitator 521 in terms of the number of revolutions per unit time (rpm). In the present embodiment, since the second agitator 522 can be rotated faster than the first agitator 521, the movement of the treatment object X can be disturbed at the time of agitation, and thus the treatment object X can be immediately agitated into a uniform state.

[0044] As the first agitator 521, an agitator having a maximum rotation speed of ≤500 rpm can be used, and as the second agitator 521, an agitator having a maximum rotation speed of ≤3000 rpm can be used. The first agitator 521 can be driven to rotate at a speed of, for example, 25 rpm to 250 rpm for carbonization treatment. The second agitator 522 can be driven to rotate at a speed of, for example, 100 rpm to 1000 rpm for carbonization treatment.

[0045] The first agitator 521 and the second agitator 522 of the present embodiment extend or hang from the top wall 51c. More specifically, the first agitator 521 and the second agitator 522 hang from the top wall 51c via a plate-shaped body 52a provided below the top wall 51c, the plate-shaped body 52a being parallel to the top wall 51c and being able to rotate horizontally.

[0046] In the present embodiment, the plate-shaped body 52a has a shape smaller than the disc shape of the top wall 51c, and is configured as a gear box to control the rotation of the stirrer 52. The plate-shaped body 52a can be horizontally rotated around an axis (hereinafter also referred to as a revolution axis C52) that extends vertically through the center of the reaction vessel 51. The first stirrer 521 and the second stirrer 522 thus suspended are positioned in the plate-shaped body 52a in a horizontal direction away from the above-mentioned axis (i.e., the revolution axis C52) to be able to move in planetary motion around the revolution axis C52.

[0047] The first stirrer 521 is configured to be able to rotate around an axis (hereinafter also referred to as a first rotation axis C521) that extends vertically through a mounting point at which the first stirrer 521 is mounted to the plate-shaped body 52a, and thereby stir the processing object X. Similarly, the second stirrer 522 is configured to be able to rotate around an axis (hereinafter also referred to as a second rotation axis C522) that extends vertically through a mounting point at which the second stirrer 522a is mounted to the plate-shaped body 52a, and thereby stir the processing object X. That is, each of the first stirrer 521 and the second stirrer 522 is configured to be able to rotate around its axis while revolving (i.e., move in planetary motion), and thereby stir the processing object X.

[0048] The revolution axis C52, the first rotation axis C521, and the second rotation axis C522 can not extend along the vertical direction, but can extend at a slight angle (e.g., 10 degrees or less) from the vertical. However, it should be noted that the angle from the vertical is preferably 5 degrees or less. In the present embodiment, the revolution axis C52, the first rotation axis C521, and the second rotation axis C522 extend in the vertical direction.

[0049] Each of the first stirrer 521 and the second stirrer 522 includes a stirring impeller that rotates around its rotation axis (i.e., the first rotation axis C521 and the second rotation axis C522) to stir the processing object X. The stirring impeller of the first stirrer 521 (hereinafter also referred to as the first stirring impeller 521c) and the stirring impeller of the second stirrer 522 (hereinafter also referred to as the second stirring impeller 522c) are positioned differently from each other in the vertical direction, as shown in Figure 3 In the present embodiment, since the second stirrer 522 rotates faster than the first stirrer 521 as described above, the processing object X can be immediately stirred into a uniform state. Further, since the stirring impeller of the second stirrer 522 (i.e., the second stirring impeller 522c) and the stirring impeller of the first stirrer 521 (i.e., the first stirring impeller 521c) are positioned separately from each other in the vertical direction, the processing object X can be brought into a uniform state more promptly.

[0050] The first stirrer 521 includes: a plurality of arms 521a extending radially outward from a first axis of rotation C521; a plurality of legs 521b extending from the respective distal ends of the plurality of arms 521a; and a first impeller 521c, each disposed at the lower end of a leg 521b. More specifically, the first stirrer 521 includes a first impeller 521c that moves along the inner wall surface 51bs (upper surface) of the bottom wall 51b to scoop up the processed object X from the bottom of the reaction vessel 51 and stir the scooped-up processed object X by revolution around its axis of revolution and rotation about its axis of rotation. Each of the first impellers 521c is disposed from the lower end of the corresponding leg 521b in a direction opposite to that toward the axis of rotation of the first stirrer 521 (i.e., the first axis of rotation C521), to combine with the corresponding leg 521b to form an inverted T-shape. The shape of this combination may be L-shaped.

[0051] The leg 521b of the first agitator 521 is positioned radially away from the first axis of rotation C521, where the leg 521b extends vertically and thus rotates around the first axis of rotation C521. That is, the first agitator 521 is configured such that the object X to be processed can be agitated not only by the first impeller 521c but also by the leg 521b.

[0052] like Figure 4 As shown, the first stirrer 521 is configured such that: when the circle drawn along the trajectory of the first rotation axis C521 in revolution is the revolution circle CV1, the radius of the revolution circle CV1 is the revolution radius rv1; the circle of the outermost trajectory drawn by the first stirring impeller 521c in rotation is the rotation circle CR1, and the radius of the rotation circle CR1 is the rotation radius rr1, which can be greater than the revolution circle rv1.

[0053] When the rotation radius rr1 of the first stirrer 521 is equal to the revolution radius rv1, the rotating circle CR1 rotates around the revolution axis C52, causing a point of the rotating circle CR1 to continuously contact the revolution axis C52, such as... Figure 5A As shown. When the radius of rotation rr1 is greater than the radius of revolution rv1, the axis of rotation C52 is always located within the circle of rotation CR1, while the circle of rotation CR1 revolves around the axis of revolution C52, as shown. Figure 5B As shown. On the other hand, when the radius of rotation rr1 is less than the radius of revolution rv1, the rotating circle CR1 revolves around the outer periphery of the axis of revolution C52, so that the trajectory of the rotating circle CR1 has a circular shape, and thus forms a region around the center of the reaction vessel 51 in which no stirring is carried out. Therefore, the radius of rotation rr1 of the first stirrer 521 can be less than the radius of revolution rv1, but is preferably equal to or greater than the radius of revolution rv1.

[0054] The rotational radius rr1 and the revolving radius rv1 of the first agitator 521 can satisfy any one of the following relationships (1) to (3):

[0055] (0.8 x rv1) < rr1 < (1.2 x rv1) (1)

[0056] (0.9 x rv1) < rr1 < (1.2 x rv1) (2)

[0057] rv1 < rr1 < (1.2 x rv1) (3)

[0058] Each of the first agitators 521 is preferably configured so that, when the processing object X is agitated, the first agitator impeller 521c is disposed to pass near the circumferential side wall 51s. When the position of the revolving axis C52 is the origin Z, and in a cross section of the reaction vessel 51 along a plane orthogonal to the revolving axis C52, the distance from the origin Z to the circumferential side wall 51s (the radius of the outer circumferential circle of the inner wall surface 51bs of the bottom wall 51b) is “r (m)”, the total length of the rotational radius rr1 and the revolving radius rv1 can be > 0.8r and < 1.0r, and can be > 0.9r and < 1.0r. Among these, the length of the rotational radius rr1 can be, for example, > 0.3r and < 0.7r.

[0059] The second agitator 522 includes a second agitator impeller 522c that rotates above the first agitator impeller 521c so as to be able to pulverize agglomerates contained in the processing object X scooped up by the first agitator 521. The second agitator 522 of the present embodiment includes a second agitator impeller 522c disposed above the upper end of the first agitator impeller 521c. The second agitator impeller 522c can be a flat plate-shaped impeller. For example, the second agitator impeller 522c can be a flat plate-shaped impeller disposed so that its plate face is substantially parallel to the direction of travel during rotation.

[0060] When the distance in the vertical direction from the inner wall surface 51bs of the bottom wall 51b to the inner wall surface 51cs of the top wall 51c is (h0), the ratio (h1 / h0) of the height (h1) of the upper edge of the second agitator impeller 522c from the inner wall surface 51bs of the bottom wall 51b to the height (h0) of the accommodation space 51a can be < 0.8. The ratio (h1 / h0) can be < 0.7, or can be < 0.6. For example, the ratio (h1 / h0) can be > 0.3. The ratio (h1 / h0) can be > 0.4.

[0061] A ratio (d1 / h0) of a distance (d1) from a lower edge of the second impeller 522c to an inner wall surface 51bs of the bottom wall 51b to a height (h0) of the accommodation space 51a can be ≥ 0.1, or can be ≥ 0.2. For example, a distance in the vertical direction from the lower edge of the second impeller 522c to an upper edge of the second impeller 522c can be ≥ 0.1h0and ≤ 0.4h0.

[0062] The second agitator 522 can include a plurality of second agitator impellers 522c. The plurality of second agitator impellers 522c can be installed at different positions in the vertical direction. For example, the number of the second agitator impellers 522c included in the second agitator 522 can be two or more and six or less. The plurality of second agitator impellers 522c can be disposed at intervals along the vertical direction. One of the second agitator impellers 522c and the remaining one of the second agitator impellers 522c can be disposed to cross each other to form an X shape in a plan view. One of the second agitator impellers 522c and the remaining one of the second agitator impellers 522c can cross each other at an angle of about 90° (for example, 80° to 90°) in a plan view.

[0063] When the plurality of second impellers 522c are provided, the upper edge of the second agitator impeller 522c means the upper edge of the second agitator impeller 522c disposed at the highest position (i.e., the highest second impeller 522c). The distance (d1) from the lower edge of the second agitator impeller 522c to the inner wall surface 51bs of the bottom wall 51b means the distance from the lower edge of the second agitator impeller 522c disposed at the lowest position (i.e., the lowest second impeller 522c) to the inner wall surface 51bs.

[0064] The highest second impeller 522c can be configured to rotate in a range of ≥ 0.3h0and ≤ 0.6h0. The lowest second impeller 522c can be configured to rotate in a range of ≥ 0.1h0and < 0.3h0.

[0065] Each of the second agitator impellers 522c has a rectangular shape as viewed in the axial direction of the second rotation axis C522. Each of the second agitator impellers 522c of the present embodiment can have a parallelogram shape. The second agitator impeller 522c having the parallelogram shape can be rotated about the intersection point of the diagonals. It can be configured such that, of the four corners of the second agitator impeller 522c, the two corners located on the front side in the direction of rotation each form an obtuse angle, and the two corners located on the rear side in the direction of rotation each form an acute angle.

[0066] The first stirring impeller 521c is mounted to the leg 521b which is provided in the first stirrer 521 at a position away from the first rotation axis C521 in the radial direction, while the second stirring impeller 522c is mounted to the rotation shaft which extends along the second rotation axis C522 in the second stirrer 522. Therefore, the revolution radius rr2 of the second stirrer 522 is equal to the length from the radially outer edge of the second stirring impeller 522c to the second rotation axis C522. The revolution radius rv2 of the second stirrer 522 can be smaller or larger than the revolution radius rv1 of the first stirrer 521, and can be equal to the revolution radius rv1 of the first stirrer 521. For example, the total length of the revolution radius rv2 and the rotation radius rr2 of the second stirrer 522 can be ≥ 0.2r and ≤ 0.8r. Among them, for example, the length of the rotation radius rr2 of the second stirrer 522 can be ≥ 0.1r and ≤ 0.5r.

[0067] The carbonization treatment apparatus 50 can be subjected to modifications without limiting the above-illustrated embodiments. For example, the carbonization treatment apparatus 50 can include two first stirrers 521. In another example, the carbonization treatment apparatus 50 can include one first stirrer 521 and two second stirrers 522.

[0068] In the illustrated embodiment, the scraper 53 is also suspended from the plate-shaped body 52a. That is, the scraper 53 is provided to move along the inner side of the circumferential side wall 51s during the planetary motion of the stirrer 52. When the treatment object X is subjected to the carbonization treatment, the treatment object X can adhere to the inner wall surface of the reaction container 51. The carbonization reaction in the treatment object X adhered to the inner wall surface is less likely to progress compared to the carbonization reaction in the treatment object X being stirred. In the present embodiment, the treatment object X is prevented from adhering to the bottom wall 51b by the first stirring impeller 521c, and the treatment object X is prevented from adhering to the circumferential side wall 51s by the scraper 53.

[0069] In the present embodiment, as described above, the scraper 53 scrapes off the treatment object X from the inner wall surface before firm adhesion of the treatment object X is processed, and thus it is possible to prevent uneven agitation, and thus it is less likely that unreacted material is formed. It is preferable that this function is applied from an area close to the surface area of the treatment object X to an area close to the bottom of the reaction vessel 51. In order to pulverize the mass of the treatment object X that has been scraped off by the scraper 53 by the second stirring impeller 522c, the positions of the upper end and the lower end of the scraper 53 can be set to correspond to the arrangement of the second stirring impeller 522c. The upper end of the scraper 53 can be positioned in a range of > 0.3ho and < 0.6ho above the inner wall surface 51bs of the bottom wall 51b, and the lower end of the scraper 53 can be positioned in a range of < 0.3ho above the inner wall surface 51bs of the bottom wall 51b. The scraper 53 can be provided so that the lower end is in contact with the inner wall surface 51bs of the bottom wall 51b.

[0070] According to the carbonization treatment method using the carbonization treatment apparatus 50, as described above, the fly ash is subjected to carbonization treatment using a gas containing carbon dioxide.

[0071] In the carbonization treatment method of the present embodiment, a heavy metal fixing agent can be used in combination in addition to the fly ash, water, and the gas containing carbon dioxide. As the heavy metal fixing agent, it is possible to use: a calcium compound such as calcium silicate, calcium hydroxide, calcium oxide, or calcium carbonate; a phosphoric acid compound such as calcium phosphate or hydroxyapatite; an inorganic fixing agent including an iron compound such as ferrous sulfate or ferrous chloride; or an organic (chelate) fixing agent including a dithiocarbamic acid-based compound.

[0072] In the carbonization treatment method of the present embodiment, a treatment object X containing fly ash and water is prepared. In order to prepare the treatment object X, the fly ash to be treated, water, and a heavy metal fixing agent are weighed separately. The weighing of the fly ash can be performed before or after the fly ash is housed in the reaction vessel 51. That is, in the present embodiment, the fly ash that has been weighed previously can be housed in the reaction vessel 51, or the fly ash and the reaction vessel 51 can be weighed together while the fly ash is added to the reaction vessel 51.

[0073] The water can be pure water, industrial water, or the like, and can be river water, lake water, or the like. It is preferable that the treatment target X at the start time of the carbonization treatment contain water in an amount of 5 parts by mass or more in 100 parts by mass of the solid content. By containing 5 parts by mass or more of water, the fly ash is hardly stirred up during the carbonization treatment, and discharge of the fly ash from the reaction vessel 51 can be suppressed. The proportion of water can be 10 parts by mass or more, or 12 parts by mass or more. The amount of water to be maintained is preferably equal to or less than a certain value such that the viscosity of the treatment target X does not excessively increase. It is preferable that the treatment target X at the start time of the carbonization treatment contain water at a ratio of 30 parts by mass or less per 100 parts by mass of the solid content. The proportion of water can be 25 parts by mass or less, or can be 22 parts by mass or less. The proportion of water can be 20 parts by mass. For this reason, it is preferable that the fly ash and the water used in the treatment be adjusted such that the proportion of water to be added to 100 parts by mass of the fly ash can be within the range described above (i.e., 10 parts by mass or more and 20 parts by mass or less).

[0074] For example, the addition of water to the fly ash is performed in the reaction vessel 51. When water is added to the fly ash, the temperature of the contact points between the water and the fly ash can be raised due to the heat of hydration, and the water partially evaporates. In the present embodiment, since the reaction vessel 51 can be sealed, the water that has been added to the fly ash in the reaction vessel 51 and thus evaporated can be absorbed again into the fly ash, so that a treatment target having an accurate amount ratio between the fly ash and the water can be prepared. The heavy metal fixing agent can be added to the fly ash together with the water, and can be added before or after the water is added.

[0075] When the water is added, the treatment target X housed in the reaction vessel 51 can be cooled by the inner wall surface by circulating the cooling liquid in the flow passage 51r by driving the cooling device 90. In the present embodiment, the scraper 53 is provided to scrape off the treatment target X adhering to the circumferential side wall 51s by the revolution of the stirrer 52. Thus, the treatment target X that has been cooled by the circumferential side wall 51s can be immediately separated from the circumferential side wall 51s to allow the treatment target X to be sequentially cooled, so that an excellent cooling efficiency can be produced.

[0076] The first stirrer 521 of the present embodiment is configured to scoop up the treatment target X adhering to the inner wall surface 51bs of the bottom wall 51b and stir the scooped-up treatment target X, and thus the provision of the flow passage of the cooling liquid in the bottom wall 51b can produce a higher cooling efficiency. That is, in the present embodiment, the cooling of the treatment target X by cooling either or both of the inner wall surface 51bs of the bottom wall 51b and the inner wall surface 51ss of the circumferential side wall 51s can produce a high cooling efficiency.

[0077] According to the present embodiment, therefore, a treatment target X having a precisely adjusted amount ratio between water and fly ash can be prepared.

[0078] After the treatment target X is prepared, the exhaust gas is circulated in the accommodation space 51a of the reaction vessel 51 to subject the fly ash contained in the treatment target X to carbonization treatment. At this time, the exhaust gas can be configured so as to be allowed to pass through the water contact device 60 and the dehumidifying device 80, and be introduced into the accommodation space 51a of the reaction vessel 51 through the gas inlet member 511 of the carbonization treatment device 50. Therefore, the exhaust gas is converted into a gas containing carbon dioxide while containing a small amount of excess water and corrosive gas, and is supplied to the carbonization treatment device 50. Therefore, in the present embodiment, corrosion of the piping system and the carbonization treatment device 50 can be suppressed. In the present embodiment, for example, the possibility of hindering carbonization treatment due to the presence of excess water is reduced, and therefore the possibility of a large variation in the water ratio of the treatment target X can be reduced.

[0079] When the exhaust gas discharged from the incinerator 10 is supplied to the carbonization treatment device 50 while hydrogen chloride remains in the exhaust gas, the hydrogen chloride reacts with the calcium compound contained in the fly ash, which causes the possibility of forming a component capable of being eluted with water during carbonization treatment. Therefore, it is preferable to remove hydrogen chloride by allowing the exhaust gas containing a low concentration, i.e., about 10 ppm, of hydrogen chloride to pass through the water contact device 60. That is, in the case where the exhaust gas containing ≥ 10 ppm of hydrogen chloride is used as a gas to be supplied to the carbonization treatment device 50, it is preferable to perform removal of hydrogen chloride from the exhaust gas to reduce the concentration of hydrogen chloride to less than 10 ppm before the exhaust gas is supplied to the carbonization treatment device 50. The concentration of hydrogen chloride of the gas to be supplied to the carbonization treatment device 50 is preferably 5 ppm or less, more preferably 1 ppm or less.

[0080] Since hydrogen chloride has a high solubility in water compared to carbon dioxide, the ventilator for use in the water contact device 60 can have a simple structure as long as the ventilator can allow the exhaust gas to pass through calm and still water, and for example, an immersed weir ventilator can be used.

[0081] The gas containing carbon dioxide can be circulated into the accommodation space 51a before or after the addition of water to the fly ash is completed. That is, the carbonization treatment can be started before or after the addition of the total amount of water.

[0082] In the carbonization treatment, the gas in the upper end region of the accommodation space 51a is discharged by the gas outlet member 512, while new gas is introduced into the accommodation space 51a from the gas inlet member 511. Since the treatment target X is greatly stirred by the stirrer 52 in the accommodation space 51a, contact between the fly ash and carbon dioxide can be achieved in good conditions, so that the carbonization treatment of the fly ash can be smoothly progressed.

[0083] In the carbonization treatment, the first agitator 521 can rotate (about its axis) at a speed of 25 rpm to 250 rpm, and the second agitator 522 can rotate (about its axis) at a speed of 100 rpm to 1000 rpm. When the carbonization treatment is performed, these agitators 52 can revolve (move in planetary motion) at a speed of 10 rpm to 60 rpm.

[0084] In the present embodiment, an additional space in which the processing object X is not accommodated can be provided on the upper side within the reaction vessel 51 to enable the processing object X to be agitated in the additional space, so that the processing object X can be homogenized in a short period of time. In the present embodiment, gas is discharged from the upper end region of the accommodation space 51a. Thus, for example, even in the case where the processing object X contains ash aggregates and the ash flies upward by pulverizing the aggregates within the reaction vessel 51, such fly ash can be prevented from being discharged from the gas outlet member 512. To prevent the ash from flying upward, all of the second agitator impellers 522c of the second agitator 522 can be configured to agitate the processing object X while being placed within the processing object X.

[0085] An additional space can be provided to occupy about 30% to 90% or 50% to 70% of the volume of the reaction vessel 51. In other words, the average height (hx) of the processing object X at the start time of the carbonization treatment can be ≥ 0.1 h0, or can be ≥ 0.3 h0. The average height (hx) can be ≤ 0.7 h0, or can be ≤ 0.5 h0. The average height (hx) of the processing object X can be adjusted to have the following relationship with the height (hi) of the upper edge of the second agitator impeller 522c:

[0086] hi ≤ hx ≤ 1.2 hi.

[0087] The average height (hx) of the processing object X means a height assuming that the processing object X is accommodated in the reaction vessel 51 to have a uniform height from the inner wall surface 51bs of the bottom wall 51b. For example, when the radius of the circumferential side wall 51s is constant in the vertical direction, the average height (hx) of the accommodation space 51a can be determined by dividing the volume of the processing object X by the area of the inner wall surface 51bs of the bottom wall 51b.

[0088] To prevent fly ash from being discharged from the gas outlet member 512, the flow rate of the gas discharged from the gas outlet member 512 can be adjusted to achieve a desired gas velocity, for example, adjusted to be ≥ 1 m / s and ≤ 5 m / s. The flow rate can be adjusted to be ≤ 4 m / s, or can be adjusted to be ≤ 3 m / s. The flow rate can be adjusted by the cross-sectional area of the discharge hole (the area of the opening facing the accommodation space: A (m 2 )) and the amount of gas discharged per unit time: V (Nm3 / min) is determined. That is, the flow rate can be determined by the following equation. The flow rate is adjusted in this way so that the emission of fly ash can be suppressed even when the amount of fly ash contained in the gas changes.

[0089] Flow rate (m / s) = (V / 60) / A

[0090] It is preferable that the gas introduced into the accommodation space 51a by the gas inlet member 511 has a constant flow rate or a higher flow rate for the purpose of promoting the carbonization treatment by generating a moderate gas flow. For example, the flow rate can be ≥ 10 m / s. The flow rate can be ≥ 12 m / s. On the other hand, introducing the gas into the accommodation space 51a at an excessively high flow rate causes ash and the like to easily fly upward inside the accommodation space 51a. In view of this, the flow rate can be ≤ 40 m / s. The flow rate can be ≤ 30 m / s, or can be ≤ 20 m / s. The flow rate can be determined in the same way as the flow rate in the gas outlet member 512.

[0091] The flow rate of the gas to be introduced into the accommodation space 51a or the flow rate of the gas to be discharged from the accommodation space 51a can be adjusted in accordance with the size of the gas inlet hole or the gas outlet hole. In a case where the gas introduced through the gas inlet hole is mostly absorbed in the treatment object, the gas outlet hole can be eliminated. Further, in a case where a solid substance and the like from which carbon dioxide is generated by decomposition are introduced into the accommodation space 51a together with the treatment object in advance, and then the carbonization treatment is performed, the gas inlet hole can also be eliminated.

[0092] The flow rates in the discharge of the gas and the supply of the gas do not need to be maintained at the above-described flow rates throughout the entire carbonization treatment time. For example, the above-described flow rates can be applied in 80% or more or 50% or more of the entire carbonization treatment time.

[0093] In order to circulate the gas in the accommodation space 51a, it is conceivable to both suck the gas from the gas outlet member 512 and blow the gas flow from the gas inlet member 511, and the latter method can be advantageous in that the latter method can suppress the emission of fly ash and the like. Therefore, when the carbonization treatment is performed, the accommodation space 51a can be maintained at a positive pressure by blowing the gas flow from the gas inlet member 511. The accommodation space 51a can be adjusted to exceed 0 kPa in gauge pressure. The pressure of the accommodation space 51a can be ≥ 1 kPa. The pressure of the accommodation space 51a can be ≤ 10 kPa, or can be ≤ 5 kPa. The pressure of the accommodation space 51a can be ≤ 3 kPa.

[0094] In the case where the exhaust gas is used for the carbonization treatment, the concentration of carbon dioxide in the gas to be introduced into the accommodation space 51a is generally ≥ 5 mass% to ≤ 30 mass%. In the case where a gas containing ≥ 90 mass% of carbon dioxide is used for the carbonization treatment, the gas introduced into the accommodation space 51a is mostly absorbed in the treatment object X. Therefore, in the case where a gas containing a high concentration of carbon dioxide is used, the pressure of the accommodation space 51a can be set to be higher than the above-mentioned pressure so as to accelerate the carbonization treatment.

[0095] In the case where a gas containing a high concentration of carbon dioxide is used, for example, the pressure of the accommodation space 51a can be ≥ 3 kPa in gauge pressure. The pressure of the accommodation space 51a can be ≥ 5 kPa, or can be ≥ 10 kPa. The pressure of the accommodation space 51a can be ≤ 30 kPa. The pressure of the accommodation space 51a can be ≤ 25 kPa, or can be ≤ 20 kPa. In order to maintain the pressure of the accommodation space 51a at these levels, a reaction vessel not having a gas discharge member can be used.

[0096] When the accommodation space 51a is maintained at a positive pressure, the above-mentioned pressure does not need to be maintained throughout the entire carbonization treatment time. For example, the above-mentioned pressure can be applied in 50% or more or 80% or more of the entire carbonization treatment time.

[0097] The above-mentioned carbonization treatment can be performed by time control. For the carbonization treatment, it can be configured so that the amount of carbon dioxide in the gas introduced into the accommodation space 51a and the amount of carbon dioxide discharged from the accommodation space 51a are measured to monitor the progress of the carbonization treatment, and the end point of the carbonization treatment is determined by the monitoring.

[0098] In the present embodiment, by performing the above-mentioned carbonization treatment method using the above-mentioned carbonization treatment apparatus, the carbonization treatment can be effectively performed while suppressing the discharge of fly ash to the outside of the apparatus. The foregoing is merely a restrictive example. In other words, the present disclosure is not limited to the above-mentioned description in any way, and various changes can be made to some extent without significantly restricting the effects of the present disclosure.

[0099] Examples

[0100] Next, the present disclosure will be described in more detail with reference to examples, without being limited thereto.

[0101] Example 1: Preparation of a Treatment Object

[0102] As Figure 2As shown, approximately 300 kg of fly ash was placed in the carbonization treatment equipment, and water was gradually added to the fly ash while it was being stirred to prepare the object to be carbonized. A total of approximately 45 kg of water was added. Regarding the fly ash, according to Notification No. 13 from the Environment Agency, the amount of lead eluted in the elution test was approximately 4.0 mg / L, and the amount of hexavalent chromium eluted was approximately 1.7 mg / L.

[0103] carbonization

[0104] Carbonization treatment involves using simulated exhaust gas containing approximately 9% carbon dioxide at a flow rate of approximately 600m³. 3 / h to 1000m 3 The process involves circulating the material to the carbonization unit at a flow rate of / h while simultaneously agitating the material prepared as described above. The flow rate at discharge time is 1.6 m / s to 2.7 m / s, with an additional 50% space. Under these conditions, 42 visual observations were performed on the interior of the outlet pipe approximately 10 minutes after treatment, confirming that fly ash emissions during carbonization were adequately prevented. The difference between the amount of carbon dioxide introduced into the carbonization unit and the amount of carbon dioxide discharged from the carbonization unit was monitored as the carbon dioxide absorption rate. It was found that approximately 5 minutes after the start of carbonization, the carbon dioxide absorption rate based on 100 parts by mass of fly ash was approximately 0.7 parts by mass, and at this time, the amount of lead eluted was approximately 0.02 mg / L, and the amount of hexavalent chromium eluted was approximately 0.1 mg / L.

[0105] Example 2: Preparation of the processing object

[0106] like Figure 2 As shown, approximately 300 kg of paper mill sludge incineration ash and 300 kg of biomass ash were placed in the carbonization treatment equipment. The ash was mixed in its dry form for approximately 30 seconds, and water was then gradually added to the mixture while stirring to prepare the material to be carbonized. A total of approximately 120 kg of water was added. Regarding the ash mixture, according to BSEN 12457-4:2002, in the leaching test, the amount of lead eluted was approximately 0.5 mg / L, and the amount of zinc eluted was approximately 0.2 mg / L.

[0107] carbonization

[0108] The exhaust component 512 is closed, and only the intake component 511 is used. Carbonization is performed by adding high-purity liquid carbon dioxide to the carbonization treatment apparatus. Approximately 20 kg of carbon dioxide is added at a flow rate of approximately 400 kg / hr. After carbonization, the amount of lead eluted is approximately 0.2 mg / L, and the amount of zinc eluted is approximately 0.1 mg / L.

[0109] As described above, according to the carbonization treatment apparatus and the carbonization treatment method, carbonization treatment can be effectively performed.

[0110] List of Reference Signs

[0111] 10: incinerator

[0112] 20: cooling tower

[0113] 30: alkaline treatment device

[0114] 40: fly ash removal device

[0115] 50: carbonization treatment apparatus

[0116] 51: reaction vessel

[0117] 51a: accommodation space

[0118] 51b: bottom wall

[0119] 51bs: inner wall surface

[0120] 51c: top wall

[0121] 51cs: inner wall surface

[0122] 51r: flow passage

[0123] 51s: circumferential wall surface

[0124] 51ss: circumferential wall surface

[0125] 52: stirrer

[0126] 52a: plate-shaped body

[0127] 53: scraper

[0128] 60: water contact device

[0129] 70: air blower

[0130] 80: dehumidifying device

[0131] 90: cooling device

[0132] 100: incineration facility

[0133] 510: material supply member

[0134] 510h: material supply hole

[0135] 510p: cover

[0136] 511: air intake member

[0137] 511h: air intake hole

[0138] 512: gas outlet member

[0139] 512h: gas outlet hole

[0140] 521a: arm

[0141] 521b: leg

[0142] 521c: first stirring impeller

[0143] 522c: second impeller

[0144] C52: axis of revolution

[0145] C521: first axis of rotation

[0146] C522: second axis of rotation

[0147] CR1: circle of rotation

[0148] CV1: circle of revolution

[0149] LE: exhaust gas line

[0150] LE1: exhaust gas discharge line

[0151] LE2: exhaust gas supply line

[0152] V1: valve

[0153] X: processing object

[0154] Z: origin

[0155] rr1: radius of rotation

[0156] rr2: radius of rotation

[0157] rv1: radius of revolution

[0158] rv2: radius of revolution

Claims

1. A carbonization treatment apparatus for subjecting solid matter contained in a treated object to carbonization treatment by contacting the treated object with carbon dioxide while stirring it, characterized in that, The apparatus includes: a reaction vessel having a housing space in which the processing object is housed; at least one agitator that rotates around a vertically extending axis to agitate the processing object housed in the housing space; and the at least one agitator moves in planetary motion in the housing space while the processing object is being agitated.

2. The carbonization processing apparatus according to claim 1, wherein the reaction vessel includes a gas intake member for sucking a gas containing the carbon dioxide into the housing space and a gas discharge member for discharging the gas from the housing space; and the gas discharge member is configured to be able to discharge the gas of an upper end region of the housing space. a cooling device for cooling an inner wall surface of the reaction vessel that is in contact with the processing object is further included.

3. The carbonization processing apparatus according to claim 1, wherein 4. The carbonization treatment apparatus according to claim 1, wherein the at least one agitator includes a plurality of agitators; the plurality of agitators includes a first agitator and a second agitator; and the second agitator is configured to be able to rotate at a higher speed than the first agitator.

5. The carbonization treatment apparatus according to claim 4, wherein the housing space of the reaction vessel has a cylindrical shape; the reaction vessel has a bottom wall that defines a bottom of the housing space, a circumferential side wall that defines a side of the housing space, and a top wall that defines a top of the housing space; the first agitator includes an agitating impeller that moves along the bottom wall so as to be able to scoop up the processing object from the bottom of the reaction vessel and agitate the scooped-up processing object while the first agitator rotates; and the second agitator includes an agitating impeller that rotates above the agitating impeller of the first agitator so as to be able to pulverize agglomerates contained in the processing object that has been scooped up by the first agitator.

6. The carbonization treatment apparatus according to any one of claims 1 to 4, wherein the housing space of the reaction vessel has a cylindrical shape; the reaction vessel has a bottom wall that defines a bottom of the housing space, a circumferential side wall that defines a side of the housing space, and a top wall that defines a top of the housing space; and the carbonization treatment apparatus further includes a scraper that moves along an inner side of the circumferential side wall to scrape off the processing object adhering to an inner wall surface of the circumferential side wall. ​ ​ ​

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