CN113865346A - Kaolin calcination cooling system and method with controllable finished product color - Google Patents
Kaolin calcination cooling system and method with controllable finished product color Download PDFInfo
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- CN113865346A CN113865346A CN202111203492.0A CN202111203492A CN113865346A CN 113865346 A CN113865346 A CN 113865346A CN 202111203492 A CN202111203492 A CN 202111203492A CN 113865346 A CN113865346 A CN 113865346A
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
- F27B19/00—Combinations of furnaces of kinds not covered by a single preceding main group
- F27B19/04—Combinations of furnaces of kinds not covered by a single preceding main group arranged for associated working
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B33/00—Silicon; Compounds thereof
- C01B33/20—Silicates
- C01B33/36—Silicates having base-exchange properties but not having molecular sieve properties
- C01B33/38—Layered base-exchange silicates, e.g. clays, micas or alkali metal silicates of kenyaite or magadiite type
- C01B33/40—Clays
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
- F27D13/00—Apparatus for preheating charges; Arrangements for preheating charges
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
- F27D15/00—Handling or treating discharged material; Supports or receiving chambers therefor
- F27D15/02—Cooling
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
- F27D17/00—Arrangements for using waste heat; Arrangements for using, or disposing of, waste gases
- F27D17/004—Systems for reclaiming waste heat
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
- F27D7/00—Forming, maintaining, or circulating atmospheres in heating chambers
- F27D7/02—Supplying steam, vapour, gases, or liquids
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Abstract
The invention discloses a kaolin calcination cooling system with controllable finished product color and a kaolin calcination cooling method, wherein the kaolin calcination cooling system comprises a suspension preheating system, a calcining furnace system, a first cooling system and a second cooling system, the calcining furnace system comprises a preheating furnace and a modification furnace, an outlet at the top of the preheating furnace is connected with an inlet at the bottom of the modification furnace, and the preheating furnace and the modification furnace are reduction zones; an oxidation zone is arranged in the oxidation furnace between the air outlet of the lowest stage cyclone preheater of the suspension preheating system and the inlet of the penultimate cyclone preheater; the discharge port of the lowest stage cyclone preheater is connected with a material inlet of a first cooling system, a fuel injection device is arranged at the material inlet of the first cooling system or a connecting pipeline of the material inlet, and a local reducing atmosphere is arranged in the first cooling system and used for cooling the material to 200-350 ℃; the first cooling system is connected with the second cooling system. The invention can produce metakaolin meeting the color control requirement, and solves the problems of high energy consumption of a preparation system, small processing capacity, difficult control of product quality and the like.
Description
Technical Field
The invention relates to the technical field of kaolin, in particular to a kaolin calcination cooling system with controllable finished product color and a kaolin calcination cooling method.
Background
China is the first major country of kaolin resources, and kaolin takes kaolinite as a main mineral and accompanies quartz, illite, goethite, diaspore, calcite and other small amount of minerals. Kaolin (Al)2O3·2SiO2·2H2O，AS2H2) Metakaolin (MK for short) can be generated by dehydration at a proper temperature (600-900 ℃). Kaolin belongs to a layered silicate structure, and layers are bonded by van der waals bonds, in which OH "ions are strongly bonded. When the kaolin is heated in the air, a plurality of structural changes occur, and when the kaolin is heated to about 600 ℃, the layered structure of the kaolin is broken due to dehydration, and a transition phase, namely metakaolin, with poor crystallinity is formed. Because the molecular arrangement of metakaolin is irregular, the metakaolin is in a thermodynamic metastable state and has gelling property under proper excitation. Metakaolin is a highly active artificial pozzolanic material which can be blended with Ca (OH)2(CH for short) and water react to generate volcanic ash, and hydration products similar to cement are generated.
By utilizing the characteristic, when used as an admixture of cement, metakaolin reacts with CH generated in the hydration process of the cement, and certain properties of the cement can be improved. Because the preparation cost of the metakaolin is lower than that of clinkerCost of preparation, CO in the preparation of metakaolin2The discharge amount is lower than that of CO in the clinker preparation process2The emission and the source of the raw material kaolin are very wide, and the metakaolin is used for replacing clinker in the concrete and cement industries in a large mixing amount under the background that the concrete and cement industries actively promote carbon emission reduction. In addition, the metakaolin also has the physical properties of small density, large specific surface area, large oil absorption rate and the like, can be applied to concrete and cement additives, can replace pigments, plastics and rubber fillers, adsorbents, 4A molecular sieves and the like, can be used as raw materials or fillers in the industries of ceramics, papermaking, rubber, coatings, petrochemicals and the like, and has higher economic added value due to wide application.
The calcination temperature, calcination atmosphere, residence time, and finished product cooling are process parameters that must be strictly controlled during the metakaolin preparation process, and these parameters will determine the quality and color of the metakaolin finished product. The calcination of kaolin with high iron content often results in the formation of metakaolin in red or pink color, and concrete or cement in red or pink color is often mistaken for poor quality material, which greatly affects the large scale use of metakaolin in the concrete and cement industry. Analyzed in principle, hematite (Fe)2O3) Reddish brown, magnetite (Fe)3O4) And wustite (FeO) is gray black, so the color of the finished product of the iron-containing metakaolin is mainly determined by the existence form of the iron phase in the finished product, and the color of the finished product of the metakaolin can be effectively changed by reducing the content of the hematite in the finished product of the metakaolin. Based on the above analysis, a reducing atmosphere was created during metakaolin preparation to introduce Fe3+Reduction to Fe2+Is an effective means for reducing the content of hematite in the metakaolin finished product so as to prepare the metakaolin meeting the requirements of the concrete and cement industries.
At present, the existing metakaolin preparation methods mainly include a fixed bed type, a semi-fixed bed type, a fluidized bed type and the like. The method for preparing metakaolin by calcining kaolin in a rotary kiln is a commonly adopted method, but the problems of high heat consumption of a system, small processing capacity, difficult control of product color and quality and the like exist when the kaolin is calcined in the rotary kiln.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides a kaolin calcining and cooling system with controllable finished product color and a method thereof, wherein the system and the method fully consider the control requirements of the concrete and cement industries on the color of the metakaolin finished product, can produce the metakaolin meeting the color control requirements, and simultaneously solve the problems of high energy consumption, small processing capacity, difficult control of product quality and the like of a metakaolin preparation system.
The invention is realized in this way, a kaolin calcining and cooling system with controllable finished product color comprises a suspension preheating system, a calcining furnace system, a first cooling system and a second cooling system, wherein the calcining furnace system comprises a preheating furnace and a modification furnace, the bottom of the preheating furnace is provided with a combustion-supporting air inlet, the top outlet of the preheating furnace is connected with the bottom inlet of the modification furnace, the top outlet of the modification furnace is connected with the inlet of the lowest stage cyclone preheater of the suspension preheating system, the discharge port of the last-but-one second stage cyclone preheater of the suspension preheating system is respectively connected with the raw material feeding port of the preheating furnace and the raw material feeding port of the modification furnace, the preheating furnace and the modification furnace are respectively provided with a fuel feeding port and a raw material feeding port, and the preheating furnace and the modification furnace are internally provided with a reduction zone;
an oxidation furnace system is arranged between the air outlet of the lowest stage cyclone preheater of the suspension preheating system and the inlet of the penultimate cyclone preheater, the oxidation furnace system comprises an oxidation furnace, the bottom inlet of the oxidation furnace is connected with the air outlet of the lowest stage cyclone preheater of the suspension preheating system, the top outlet of the oxidation furnace is connected with the inlet of the penultimate cyclone preheater of the suspension preheating system, a fuel feeding port and a combustion-supporting air inlet are arranged on the oxidation furnace, and an oxidation area is arranged in the oxidation furnace;
the material outlet of the lowest stage cyclone preheater of the suspension preheating system is connected with a material inlet of a first cooling system, the first cooling system comprises at least one stage of cyclone cooler I, the cooling medium of the first cooling system is conventional air, a fuel injection device is arranged at the material inlet of the first cooling system or a connecting pipeline of the material inlet, a local reducing atmosphere is arranged in the first cooling system, the first cooling system is used for cooling the material to 350 ℃, an air outlet of the first cooling system is respectively connected with a combustion-supporting air inlet of the preheating furnace and a combustion-supporting air inlet of the oxidizing furnace, a material outlet of the first cooling system is connected with a material inlet of a second cooling system, the second cooling system comprises at least one stage of cyclone cooler II, and the cooling medium of the second cooling system is conventional air.
Preferably, the preheating furnace consists of a preheating furnace cone, a preheating furnace cylinder and a preheating furnace throat from bottom to top in sequence, wherein a fuel feeding port of the preheating furnace is positioned on the preheating furnace cone, and a raw material feeding port of the preheating furnace is positioned on the preheating furnace cylinder;
the modifying furnace sequentially comprises a modifying furnace cone and a modifying furnace cylinder from bottom to top, wherein a fuel feeding port of the modifying furnace is positioned in the middle of the modifying furnace cone and the modifying furnace cylinder, and a raw material feeding port of the modifying furnace is respectively positioned at the bottom and the middle of the modifying furnace cylinder;
the oxidation furnace is sequentially composed of an oxidation furnace cone and an oxidation furnace cylinder from bottom to top, a fuel feeding port of the oxidation furnace is positioned on the middle parts of the oxidation furnace cone and the oxidation furnace cylinder, and a combustion-supporting air inlet of the oxidation furnace is positioned on the oxidation furnace cylinder.
Preferably, the device also comprises a drying and crushing system for drying and crushing the raw materials, wherein a material outlet of the drying and crushing system is sequentially connected with the suspension preheating system through a lifting machine and a feeding device, or the material outlet of the drying and crushing system is connected with the suspension preheating system through a cyclone separator; and a heat source inlet of the drying and crushing system is connected with an air outlet of the first cooling system, and/or is connected with an air outlet of the second cooling system, and/or is connected with an air outlet of the suspension preheating system.
The method for calcining and cooling the kaolin with controllable finished product color by adopting the system comprises the steps that the raw materials enter a calciner system after being preheated by a suspension preheating system, a combustion environment of a reducing atmosphere with an excess air coefficient less than 1.0 is formed in the calciner system, and a combustion environment of an oxidizing atmosphere with an excess air coefficient greater than 1.0 is formed in an oxidation furnace; the calcining temperature in the calcining furnace system is 650-1000 ℃, the flue gas formed by incomplete combustion of fuel and decomposition of kaolin in the calcining furnace system enters the lowest stage cyclone preheater of the suspension preheating system along with decomposed materials after leaving the calcining furnace system, the flue gas then enters the oxidizing furnace system, and CO in the flue gas is fully reacted and unburnt fuel is fully burnt in the oxidizing furnace system; the material separated by the lowest stage cyclone preheater of the suspension preheating system enters a first cooling system, the cooling medium of the first cooling system is conventional air, fuel with a certain proportion is sprayed into a material inlet or a connecting pipeline to form a local reducing atmosphere around the material, the material is cooled to 350 ℃ through the first cooling system, and then enters a second cooling system, and is cooled to 60-150 ℃ through the second cooling system, so that the metakaolin with controllable color of the finished product is obtained.
Preferably, the excess air coefficient in the calcining furnace system is 0.5-1.0; the excess air coefficient in the oxidation furnace is 1.0-1.2.
Preferably, the fuel injection ratio of the first cooling system is 0.5-1% of the raw material amount entering the suspension preheating system.
Preferably, the flue gas at the outlet of the first cooling system enters the preheating furnace, the oxidizing furnace and the drying and crushing system, and the flue gas at the outlet of the second cooling system enters the drying and crushing system.
Preferably, the cooling medium of the second cooling system is conventional air.
Preferably, the retention time of the gas in the calciner system is 2-10 s.
The specific principle of the invention is as follows:
the key to controlling the color of the metakaolin finished product is the control of reduction calcination and cooling. Firstly, in the preferred calcining temperature of the calcining furnace system, the kaolin can be fully decomposed to form metakaolin, and the metakaolin can be prevented from crystallization and precipitation and losing activity. In order to control the color of the metakaolin finished product, the invention reasonably designs the combustion-supporting air quantity and the fuel consumption of the calcining furnace system in the process of decomposing the metakaolin into metakaolin,so that the fuel in the calcining furnace system is not completely combusted to form a reducing atmosphere (the excess air coefficient is less than 1.0), and further the Fe in the raw material is reduced3+Reduction to Fe2+And finally exists in the form of magnetite, so that the metakaolin finished product presents a gray black color. The flue gas formed by incomplete combustion of the fuel and decomposition of the kaolin in the calciner system leaves the calciner system, enters the suspension preheating system and then enters the oxidation furnace, and part of air subjected to heat exchange by the first cooling system enters the oxidation furnace and fully reacts with unburnt fuel and CO in the flue gas, so that full combustion of the fuel and full release of heat energy are ensured. Secondly, in the cooling process of the high-temperature metakaolin, the cooling atmosphere and the cooling temperature control need to be comprehensively considered. Through experimental research, if the first cooling system fuel injection device injects a certain proportion of fuel (such as coal powder, natural gas and H)2Etc.) to form a local reducing atmosphere around the material, reducing and calcining the prepared metakaolin with Fe2+The magnetite in the form can not be oxidized into Fe again in the cooling link3+(ii) a Experimental research proves that Fe is contained in metakaolin prepared by reduction calcination2+The magnetite in the form is in a stable state in the temperature range of 300-350 ℃ and below, and can not be oxidized into Fe again even if being contacted with the conventional air3+. Based on the theoretical research work, the invention adopts the fuel injection device of the first cooling system to inject a certain proportion of fuel (such as coal powder, natural gas and H) in consideration of the cooling atmosphere and the cooling temperature control2Etc.) to form local reducing atmosphere around the material, so as to prevent the high-temperature material from being oxidized by air in the cooling process, thereby realizing cooling of the material in the first cyclone cooler of the first cooling system and ensuring controllable color. Through detailed theoretical calculation, the thermal material can be quenched to the temperature range of 300-350 ℃ and below. The material quenched by the first cooling system enters the second cooling system and is cooled to about 100 ℃ by conventional air.
In the process, raw material powder meeting the production requirement is obtained after the kaolin raw material is subjected to a raw material pretreatment procedure. Raw meal powder is dried by a drying and crushing system and is fed into a suspension preheating system after being subjected to gas-solid separation by a cyclone separator. The raw material powder is preheated and separated from gas and solid in a cyclone preheater of the suspension preheating system, and the raw material powder after multiple heat exchange and gas and solid separation enters a calcining furnace system from a penultimate cyclone preheater of the suspension preheating system. The temperature distribution in the preheating furnace and the modifying furnace is monitored in real time by arranging a plurality of temperature measuring points in a layering manner in the height direction of the preheating furnace and the modifying furnace, and the temperature distribution in the preheating furnace and the modifying furnace is controlled within a reasonable range by adjusting the amount of fuel and the amount of material fed into the preheating furnace and the modifying furnace, so that the reasonable temperature distribution in the preheating furnace and the modifying furnace can ensure the full decomposition of kaolin and simultaneously ensure that the kaolin is not over-burnt, and the activity of the finished metakaolin meets the requirements of subsequent production. The fuel in the calciner system is combusted to release a large amount of heat for decomposition of kaolin, the decomposed hot materials leave the calciner system, and then the hot materials and hot flue gas are subjected to gas-solid separation in a lowest stage cyclone preheater of the suspension preheating system and then enter a first cooling system. The fuel injection device injects fuel with a certain proportion into the material inlet or the connecting pipeline, the fuel forms local reducing atmosphere around the material, and the high-temperature material is prevented from being oxidized by air in the cooling process, so that the material is cooled and separated from gas and solid in the first cyclone cooler of the first cooling system, and the color is ensured to be controllable. And the material cooled by the first cooling system enters the second cooling system from the first cooling system after gas-solid separation. And the material is further cooled and separated from gas and solid in the cyclone cooler II of the second cooling system, finally leaves from the blanking pipe of the cyclone cooler II at the lowest stage of the second cooling system, and falls into a finished product zipper machine to finally obtain a finished product meeting the requirement.
And the normal temperature air enters the second cooling system, then the material entering the second cooling system is cooled, the air after heat exchange leaves from the second air outlet of the uppermost stage cyclone cooler of the second cooling system, and then the air enters the drying and crushing system to dry the raw material. Another strand of normal temperature air enters a first cooling system, then cools the materials entering the first cooling system, the air after heat exchange leaves from an air outlet of a first cyclone cooler at the uppermost stage of the first cooling system, and then the air is divided into the following three paths: the first path enters a calcining furnace system through the bottom of a preheating furnace, and the second path enters a suspension preheating systemThe third way of the oxidation furnace connected above the lowest stage cyclone preheater is used for drying raw materials or carrying out other forms of waste heat utilization in a drying and crushing machine. The excess air coefficient in the calcining furnace system is less than 1.0 by reasonably controlling the air quantity and the fuel quantity entering the calcining furnace system, and the fuel in the calcining furnace system is incompletely combusted to form a reducing atmosphere, so that Fe in the raw materials is reduced3+Reduction to Fe2+And finally exists in the form of magnetite, so that the metakaolin finished product presents a gray black color. The method comprises the steps that flue gas formed by incomplete combustion of fuel and decomposition of kaolin in a calciner system leaves the calciner system, enters a suspension preheating system and then enters an oxidation furnace system, part of air subjected to heat exchange by a first cooling system enters an oxidation furnace and fully reacts with unburned fuel and CO in the flue gas to ensure full burn-out of the fuel and full release of heat energy, raw material powder fed into the suspension preheating system is subjected to multiple preheating and gas-solid separation, finally leaves from an air outlet of a cyclone preheater at the uppermost stage of the suspension preheating system, enters a drying and crushing system to dry the raw material, and finally the flue gas after waste heat utilization is subjected to gas-solid separation by a cyclone separator, then enters a dust collector and a flue gas treatment system, and is discharged into the atmosphere after treatment.
The invention has the following advantages and beneficial effects:
1) the calcining furnace system provided by the invention reasonably designs the combustion-supporting air quantity and the fuel consumption, so that the fuel in the calcining furnace system is not completely combusted, the whole calcining furnace system is in a reducing atmosphere, and further the Fe in the raw materials is reduced3+Reduction to Fe2 +The content of hematite in the metakaolin is greatly reduced from the source, and the difficulty of controlling the color of the metakaolin finished product is effectively reduced.
2) The calcining furnace system and the oxidizing furnace system provided by the invention are connected through the cyclone preheater, and Fe in the raw materials3+Is reduced to Fe in a calciner system2+Fe in metakaolin2+And finally exists in the form of magnetite, so that the metakaolin finished product presents a gray black color. The prepared metakaolin is subjected to gas-solid separation by a cyclone preheater and then sequentially enters a first cooling system and a second cooling system, and is sprayed into a cooling system through a fuel injection device in the first cooling systemThe fuel with a fixed proportion enters the material inlet or the connecting pipeline, and the fuel forms local reducing atmosphere around the material, so that the high-temperature material is prevented from being oxidized by air in the cooling process, the material is cooled and separated from gas and solid in the first cyclone cooler of the first cooling system, and the color is controllable. The oxidation furnace provided by the invention fully utilizes the air after heat exchange of the first cooling system, and fully reacts with unburned fuel and CO in the flue gas entering the oxidation furnace, so that the full burnout of the fuel and the full release of heat energy are ensured while the environment pollution caused by CO discharge is avoided, and the operation cost of the system is reduced.
3) The invention is provided with a first cooling system and a second cooling system which are arranged in sequence, and the two systems have definite function positioning. Wherein the first cooling system fuel injection device injects a certain proportion of fuel (such as pulverized coal, natural gas and H)2Etc.) the fuel forms a local reducing atmosphere around the material to avoid Fe in the metakaolin2+The magnetite in the form is oxidized to Fe in contact with a large amount of oxygen during cooling3+(ii) a Meanwhile, the quenching air quantity and the fuel mixing proportion are reasonably designed, and the metakaolin is cooled to a safe temperature range of 300-350 ℃ and below through the first stage. The second cooling system makes full use of the conventional air to carry out secondary cooling on the metakaolin to 60-150 ℃.
4) The flue gas and the air at the outlets of the suspension preheating system, the first cooling system and the second cooling system are fully recycled, so that the heat consumption of the system can be effectively reduced, and the production cost is reduced.
Drawings
FIG. 1 is a flow chart of a kaolin calcination cooling system with controllable finished color according to an embodiment of the present invention.
In the figure: 1. a suspension preheating system; 1-1, a cyclone preheater; 1-2, an oxidation furnace; 2. a calciner system; 2-1, preheating a furnace; 2-2, a modification furnace; 3. a first cooling system; 3-1, a first cyclone cooler; 4. a second cooling system; 4-1, a second cyclone cooler; 5. a drying and crushing system; 6. a cyclone separator.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
In the description of the present invention, it should be noted that the terms "upper", "lower", "top", "bottom", "inner", "outer", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present invention. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.
In the description of the present invention, it is to be noted that, unless otherwise explicitly specified or limited, the terms "connected" and "connected" are to be interpreted broadly, e.g., as being fixed or detachable or integrally connected; may be a mechanical connection; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
Examples
Referring to fig. 1, the present embodiment provides a kaolin calcination cooling system with controllable finished product color, which includes a drying and crushing system 5 for drying and crushing raw materials, a suspension preheating system 1, a calciner system 2, a first cooling system 3, and a second cooling system 4.
And a material outlet of the drying and crushing system 5 is connected with the suspension preheating system 1 through a cyclone separator 6, and separated flue gas enters a dust collector and a flue gas treatment system and is discharged into the atmosphere after being treated. And a heat source inlet of the drying and crushing system 5 is connected with an air outlet of the first cooling system 3, and/or is connected with an air outlet of the second cooling system 4, and/or is connected with an air outlet of the suspension preheating system 1.
The suspension preheating system 1 comprises a multistage cyclone preheater 1-1, a high-efficiency material scattering device, a connecting pipeline and the like, the preferred stage number of the cyclone preheater 1-1 of the suspension preheating system 1 is two to four, and the two-stage cyclone preheater 1-1 is arranged in the embodiment and used for preheating raw materials. The calcining furnace system 2 comprises a high-efficiency material scattering device, a combustion-supporting air inlet pipeline, a preheating furnace 2-1, a first combustor arranged on the conical part of the preheating furnace 2-1, a modifying furnace 2-2, a second combustor arranged on the conical part of the modifying furnace 2-2, a third combustor arranged in the middle of the modifying furnace 2-2, a flue gas outlet pipeline and the like, wherein a fuel feeding port and a raw material feeding port are respectively arranged on the preheating furnace 2-1 and the modifying furnace 2-2, a discharge port of a penultimate cyclone preheater 1-1 of the suspension preheating system 1 is respectively connected with the raw material feeding port of the preheating furnace 2-1 and the raw material feeding port of the modifying furnace 2-2, and a reduction zone is arranged in the preheating furnace 2-1 and the modifying furnace 2-2.
The bottom of the preheating furnace 2-1 is provided with a combustion-supporting air inlet, the preheating furnace 2-1 sequentially comprises a preheating furnace cone, a preheating furnace cylinder and a preheating furnace necking from bottom to top, a fuel feeding port of the preheating furnace 2-1 is positioned on the preheating furnace cone, and a raw material feeding port of the preheating furnace 2-1 is positioned on the preheating furnace cylinder; the modification furnace 2-2 sequentially comprises a modification furnace cone and a modification furnace cylinder from bottom to top, a fuel feeding port of the modification furnace 2-2 is positioned on the middle parts of the modification furnace cone and the modification furnace cylinder, and a raw material feeding port of the modification furnace 2-2 is respectively positioned on the bottom and the middle part of the modification furnace cylinder; the top outlet of the preheating furnace 2-1 is connected with the bottom inlet of the modifying furnace 2-2, and the top outlet of the modifying furnace 2-2 is connected with the inlet of the lowest stage cyclone preheater 1-1 of the suspension preheating system 1.
An oxidation furnace system is arranged between the air outlet of the lowest stage cyclone preheater 1-1 and the inlet of the penultimate cyclone preheater 1-1 of the suspension preheating system 1, the oxidation furnace system comprises a hot air inlet pipeline, an oxidation furnace 1-2, a fourth burner arranged on the cone part of the oxidation furnace 1-2, a fifth burner arranged in the middle of the oxidation furnace 1-2, a flue gas outlet pipeline and the like, the bottom inlet of the oxidation furnace 1-2 is connected with the air outlet of the lowest stage cyclone preheater 1-1 of the suspension preheating system 1, and the top outlet of the oxidation furnace 1-2 is connected with the inlet of the penultimate cyclone preheater 1-1 of the suspension preheating system 1. At the moment, a discharge port of the cyclone separator 6 is arranged on a connecting pipeline between an outlet of the oxidation furnace 1-2 and an inlet of the penultimate cyclone preheater 1-1, a fuel feeding port and a combustion-supporting air inlet are arranged on the oxidation furnace 1-2, the oxidation furnace 1-2 sequentially comprises an oxidation furnace cone and an oxidation furnace cylinder from bottom to top, the fuel feeding port of the oxidation furnace 1-2 is positioned on the middle parts of the oxidation furnace cone and the oxidation furnace cylinder, the combustion-supporting air inlet of the oxidation furnace 1-2 is positioned on the oxidation furnace cylinder, and an oxidation area is arranged in the oxidation furnace 1-2.
The suspension preheating system 1 is characterized in that a discharge port of a lowest stage cyclone preheater 1-1 is connected with a material inlet of a first cooling system 3, the cooling mode of the first cooling system 3 is air cooling, a cooling medium of the first cooling system 3 is conventional air, the first cooling system 3 is at least one stage of suspension cooling, the embodiment is one stage of suspension cooling and comprises a first stage cyclone cooler 3-1, a high-efficiency material scattering device, a connecting pipeline, a fuel injection device and the like, the material inlet of the first cooling system 3 or a connecting air pipe of the material inlet is provided with the fuel injection device, and the fuel injection device of the first cooling system 3 injects fuel (such as pulverized coal, natural gas and H) with a certain proportion2Etc.) fuel is used to form local reducing atmosphere around the material, so that Fe is contained in metakaolin prepared by reduction calcination2+The magnetite in the form can not be oxidized into Fe again in the cooling link3+The first cooling system 3 cools the materials to be 200-350 ℃, and the air outlet of the first cooling system 3 is respectively connected with the combustion-supporting air inlet of the preheating furnace 2-1, the combustion-supporting air inlet of the oxidizing furnace 1-2 and the heat source inlet of the drying and crushing system 5; the material outlet of first cooling system 3 is connected with the material inlet of second cooling system 4, the cooling method of second cooling system 4 is forced air cooling, the coolant of second cooling system 4 is conventional air, second cooling system 4 is at least one-level suspension cooling, and this embodiment is second grade suspension cooling, including second grade, high-efficient material device and connecting tube etc. spilt, the gas outlet of second cooling system 4 is connected with the heat source entry of broken system 5 of drying.
In addition, for the material collapsing risk that the system cuts off the power supply suddenly or other troubles lead to appear in avoiding production process, be provided with emergent surge bin in second cooling system 4 coolant inlet bottom, emergent surge bin entrance is provided with the valve, and when the system cuts off the power supply suddenly or other troubles appear, the last valve of emergent surge bin is opened, and finished product metakaolin unloads finished product zip fastener machine through emergent surge bin, ensures system safety.
The method for calcining and cooling the kaolin with controllable finished product color comprises the following steps:
the method comprises the steps that after being dried and crushed by a drying and crushing system 5, raw materials are collected by a cyclone separator 6 and are sent into a suspension preheating system 1, the raw materials enter a calcining furnace system 2 after being preheated by the suspension preheating system 1, the calcining temperature in the preheating furnace 2-1 and a modification furnace 2-2 is controlled to be 650-1000 ℃ by adjusting the amount of air, the amount of fuel and the amount of materials fed into a preheating furnace 2-1 and a modification furnace 2-2, and a combustion environment of a reducing atmosphere is formed in the calcining furnace system 2 (the coefficient of excess air in the calcining furnace system 2 is less than 1.0), so that the fuel is not fully combusted, kaolin is fully decomposed, and Fe in the raw materials is fully combusted3+Reduction to Fe2+Fe in metakaolin2+Finally, the metakaolin exists in a magnetite form, so that the metakaolin finished product presents a gray black color, and meanwhile, the metakaolin is ensured not to be over-burnt, and the activity of the metakaolin finished product meets the requirements of subsequent production. The residence time of the gas in the calcining furnace system 2 is 2-10 s.
The decomposed hot materials and hot flue gas leave a calcining furnace system 2 and enter a lowest stage cyclone preheater 1-1 of a suspension preheating system 1 for gas-solid separation, the hot flue gas then enters an oxidizing furnace system (the excess air coefficient in the oxidizing furnace system is more than 1.0), a combustion environment of an oxidizing atmosphere is formed in the oxidizing furnace 1-2 by adjusting the amount of air and the amount of fuel fed into the oxidizing furnace system, unburned fuel in the hot flue gas is fully burned out and fully reacts with CO, and then the hot flue gas continuously moves upwards to preheat raw materials.
The decomposed hot material (metakaolin) enters a first cooling system 3, the cooling medium of the first cooling system 3 is conventional air, fuel with a certain proportion is sprayed into a material inlet or a connecting pipeline of the first cooling system 3 through a fuel injection device, so that a local reducing atmosphere is formed around the material, and Fe is used as Fe in the metakaolin2+The magnetite in the form of magnetite is not oxidized again to Fe in the cooling process3+The material is cooled to 350 ℃ through the first cooling system 3, and the hot material is cooled and separated from gas and solid in a cyclone cooler I3-1 of the first cooling system 3; the flue gas at the outlet of the first cooling system 3 enters a preheating furnace 2-1, an oxidation furnace 1-2 and a drying and crushing system 5.
The material cooled by the first cooling system 3 enters the second cooling system 4, the cooling medium of the second cooling system 4 is conventional air, the material is cooled to 60-150 ℃ by the second cooling system 4, the material is further cooled and gas-solid separated in the cyclone cooler II 4-1 of the second cooling system 4, and finally the material leaves from the blanking pipe of the cyclone cooler II 4-1 at the lowest stage and falls into a finished product zipper machine to obtain a finished product meeting the requirement. The flue gas at the outlet of the second cooling system 4 enters the drying and crushing system 5 again.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: it is to be understood that modifications may be made to the technical solutions described in the foregoing embodiments, or some or all of the technical features may be equivalently replaced, and the modifications or the replacements may not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.
Claims (9)
1. A kaolin calcination cooling system with controllable finished product color is characterized by comprising a suspension preheating system, a calcining furnace system, a first cooling system and a second cooling system, wherein the calcining furnace system comprises a preheating furnace and a modification furnace, the bottom of the preheating furnace is provided with a combustion-supporting air inlet, the top outlet of the preheating furnace is connected with the bottom inlet of the modification furnace, the top outlet of the modification furnace is connected with the inlet of the lowest stage cyclone preheater of the suspension preheating system, the discharge port of the last-but-one stage cyclone preheater of the suspension preheating system is respectively connected with a raw material feeding port of the preheating furnace and a raw material feeding port of the modification furnace, the preheating furnace and the modification furnace are respectively provided with a fuel feeding port and a raw material feeding port, and the preheating furnace and the modification furnace are internally provided with a reduction zone;
an oxidation furnace system is arranged between the air outlet of the lowest stage cyclone preheater of the suspension preheating system and the inlet of the penultimate cyclone preheater, the oxidation furnace system comprises an oxidation furnace, the bottom inlet of the oxidation furnace is connected with the air outlet of the lowest stage cyclone preheater of the suspension preheating system, the top outlet of the oxidation furnace is connected with the inlet of the penultimate cyclone preheater of the suspension preheating system, a fuel feeding port and a combustion-supporting air inlet are arranged on the oxidation furnace, and an oxidation area is arranged in the oxidation furnace;
the material outlet of the lowest stage cyclone preheater of the suspension preheating system is connected with a material inlet of a first cooling system, the first cooling system comprises at least one stage of cyclone cooler I, the cooling medium of the first cooling system is conventional air, a fuel injection device is arranged at the material inlet of the first cooling system or a connecting pipeline of the material inlet, a local reducing atmosphere is arranged in the first cooling system, the first cooling system is used for cooling the material to 350 ℃, an air outlet of the first cooling system is respectively connected with a combustion-supporting air inlet of the preheating furnace and a combustion-supporting air inlet of the oxidizing furnace, a material outlet of the first cooling system is connected with a material inlet of a second cooling system, the second cooling system comprises at least one stage of cyclone cooler II, and the cooling medium of the second cooling system is conventional air.
2. The kaolin calcination cooling system with controllable finished product color according to claim 1, wherein the preheating furnace is composed of a preheating furnace cone, a preheating furnace cylinder and a preheating furnace throat from bottom to top in sequence, the fuel feeding port of the preheating furnace is positioned on the preheating furnace cone, and the raw material feeding port of the preheating furnace is positioned on the preheating furnace cylinder;
the modifying furnace sequentially comprises a modifying furnace cone and a modifying furnace cylinder from bottom to top, wherein a fuel feeding port of the modifying furnace is positioned on the middle parts of the modifying furnace cone and the modifying furnace cylinder, and a raw material feeding port of the modifying furnace is respectively positioned at the bottom and the middle part of the modifying furnace cylinder;
the oxidation furnace is sequentially composed of an oxidation furnace cone and an oxidation furnace cylinder from bottom to top, a fuel feeding port of the oxidation furnace is positioned on the middle parts of the oxidation furnace cone and the oxidation furnace cylinder, and a combustion-supporting air inlet of the oxidation furnace is positioned on the oxidation furnace cylinder.
3. The kaolin calcination cooling system with controllable finished product color according to claim 1, further comprising a drying and crushing system for drying and crushing raw materials, wherein a material outlet of the drying and crushing system is connected with the suspension preheating system through a lifter and a feeding device in sequence, or a material outlet of the drying and crushing system is connected with the suspension preheating system through a cyclone separator; and a heat source inlet of the drying and crushing system is connected with an air outlet of the first cooling system, and/or is connected with an air outlet of the second cooling system, and/or is connected with an air outlet of the suspension preheating system.
4. A method for preparing kaolin calcination cooling with controllable finished product color according to the system of any one of claims 1 to 3, wherein the method comprises the steps of preheating raw materials by a suspension preheating system, then feeding the preheated raw materials into a calciner system, forming a combustion environment of a reducing atmosphere with an excess air coefficient less than 1.0 in the calciner system, and forming a combustion environment of an oxidizing atmosphere with an excess air coefficient greater than 1.0 in an oxidation furnace; the calcining temperature in the calcining furnace system is 650-1000 ℃, the flue gas formed by incomplete combustion of fuel and decomposition of kaolin in the calcining furnace system enters the lowest stage cyclone preheater of the suspension preheating system along with decomposed materials after leaving the calcining furnace system, the flue gas then enters the oxidizing furnace system, and CO in the flue gas is fully reacted and unburnt fuel is fully burnt in the oxidizing furnace system; the material separated by the lowest stage cyclone preheater of the suspension preheating system enters a first cooling system, the cooling medium of the first cooling system is conventional air, fuel with a certain proportion is sprayed into a material inlet or a connecting pipeline to form a local reducing atmosphere around the material, the material is cooled to 350 ℃ through the first cooling system, and then enters a second cooling system, and is cooled to 60-150 ℃ through the second cooling system, so that the metakaolin with controllable color of the finished product is obtained.
5. The method for calcining and cooling the kaolin with controllable finished product color according to claim 4, wherein the coefficient of excess air in the calcining furnace system is 0.5-1.0; the excess air coefficient in the oxidation furnace is 1.0-1.2.
6. The method for cooling and calcining kaolin whose final color is controllable according to claim 4, wherein the fuel injection ratio of the first cooling system is 0.5-1% of the raw material amount entering the suspension preheating system.
7. The method for calcining and cooling the kaolin with the controllable color as claimed in claim 4, wherein the flue gas from the outlet of the first cooling system enters the preheating furnace, the oxidizing furnace and the drying and crushing system, and the flue gas from the outlet of the second cooling system enters the drying and crushing system.
8. The method for calcination cooling of kaolin with controllable color according to claim 4, wherein the cooling medium of the second cooling system is conventional air.
9. The method for calcining and cooling the kaolin with controllable finished product color according to claim 4, wherein the retention time of the gas in the calciner system is 2-10 s.
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