CN113267053B - System and method for producing cement clinker by using full-oxygen combustion circulation preheating - Google Patents

System and method for producing cement clinker by using full-oxygen combustion circulation preheating Download PDF

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CN113267053B
CN113267053B CN202110506406.7A CN202110506406A CN113267053B CN 113267053 B CN113267053 B CN 113267053B CN 202110506406 A CN202110506406 A CN 202110506406A CN 113267053 B CN113267053 B CN 113267053B
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cooling
flue gas
gas
preheater
cement clinker
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CN113267053A (en
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陈昌华
彭学平
代中元
吴杰
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Tianjin Cement Industry Design and Research Institute Co Ltd
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Tianjin Cement Industry Design and Research Institute Co Ltd
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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
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B7/00—Hydraulic cements
    • C04B7/36—Manufacture of hydraulic cements in general
    • C04B7/43—Heat treatment, e.g. precalcining, burning, melting; Cooling
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B7/00—Hydraulic cements
    • C04B7/36—Manufacture of hydraulic cements in general
    • C04B7/43—Heat treatment, e.g. precalcining, burning, melting; Cooling
    • C04B7/432—Preheating without addition of fuel
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B7/00—Hydraulic cements
    • C04B7/36—Manufacture of hydraulic cements in general
    • C04B7/43—Heat treatment, e.g. precalcining, burning, melting; Cooling
    • C04B7/44—Burning; Melting
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B7/00—Hydraulic cements
    • C04B7/36—Manufacture of hydraulic cements in general
    • C04B7/43—Heat treatment, e.g. precalcining, burning, melting; Cooling
    • C04B7/47—Cooling ; Waste heat management
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B7/00—Hydraulic cements
    • C04B7/36—Manufacture of hydraulic cements in general
    • C04B7/43—Heat treatment, e.g. precalcining, burning, melting; Cooling
    • C04B7/47—Cooling ; Waste heat management
    • C04B7/475—Cooling ; Waste heat management using the waste heat, e.g. of the cooled clinker, in an other way than by simple heat exchange in the cement production line, e.g. for generating steam
    • 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
    • F27B7/00—Rotary-drum furnaces, i.e. horizontal or slightly inclined
    • F27B7/20—Details, accessories, or equipment peculiar to rotary-drum furnaces
    • F27B7/34—Arrangements of heating devices
    • 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
    • F27B7/00—Rotary-drum furnaces, i.e. horizontal or slightly inclined
    • F27B7/20—Details, accessories, or equipment peculiar to rotary-drum furnaces
    • F27B7/38—Arrangements of cooling devices
    • 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
    • F27D2013/007—Apparatus for preheating charges; Arrangements for preheating charges using a rotary furnace

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Ceramic Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Organic Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Furnace Details (AREA)

Abstract

The invention provides a system and a method for producing cement clinker by using total oxygen combustion circulating preheating, wherein the system comprises a preheater, a decomposing furnace, a smoke chamber, a rotary kiln and a cooler, the preheater comprises a conventional preheater and a smoke circulating preheater, the cooler comprises a first cooling area and a second cooling area, the first cooling area comprises a first cooling subarea and a second cooling subarea, the mixed gas of high-concentration pure oxygen and carbon dioxide smoke is introduced into the inlet of the first cooling subarea, the outlet of the first cooling subarea is communicated with the air inlet of the rotary kiln, the first cooling gas discharged from the outlet of the first cooling subarea is used as secondary air to enter the air inlet of the rotary kiln, the carbon dioxide smoke is introduced into the inlet of the second cooling subarea, the outlet of the second cooling subarea is communicated with the air inlet of the rotary kiln through a first pipeline, the second cooling gas discharged from the outlet of the second cooling subarea is controlled to enter the air inlet of the rotary kiln as four-time air, thereby adjusting O in the mixed gas in the rotary kiln2Concentration, and further controlling the flame temperature of the total oxygen combustion of the rotary kiln.

Description

System and method for producing cement clinker through total oxygen combustion circulation preheating
Technical Field
The invention belongs to the technical field of cement processes, and particularly relates to a system and a method for producing cement clinker by using oxy-fuel combustion and cyclic preheating.
Background
As global climate warms, the emission of carbon dioxide is of great concern. A large amount of carbon dioxide is generated in the cement production process, and according to statistics, 0.6-0.7 t of carbon dioxide is discharged when 1t of cement is produced. Carbon dioxide in the cement kiln waste gas mainly comes from the following two aspects:
1. the carbon dioxide generated in the fuel combustion flue gas accounts for about 40%.
2. The carbon dioxide produced by decomposition of the carbonate in the feedstock is present in a proportion of about 60%.
The International Energy Agency (IEA) and the cement sustainable development initiative (CSI) collaborative development "2050 roadmap for cement technology" states that: the carbon capture and sequestration technology is the most feasible new technology for reducing carbon dioxide emission in the cement industry at present, and the carbon dioxide emission can be reduced by 56% in 2050. Wherein the oxy-fuel combustion technology has better development prospect in the carbon capture and storage technology.
Oxy-fuel combustion refers to the combustion of fuel by using industrial oxygen instead of air, so that the fuel can be combusted more completely, and compared with air combustion, oxy-fuel combustion has the following advantages:
1) compared with the air combustion, the oxy-fuel combustion process has the advantages that about 79 percent of nitrogen in the air does not participate in the combustion any more, so that the flame temperature can be increased;
2) the content of nitrogen in the flue gas is low, the combustion product is a triatomic product, the heat transfer effect of a triatomic substance is higher than that of a diatomic substance, and the heating efficiency is improved;
3) the nitrogen does not participate in smoke exhaust any more, so that the amount of smoke can be greatly reduced, and the heat loss of the smoke exhaust is reduced;
4) the oxy-fuel combustion technology can save fuel, reduce the emission of NOx and meet the requirement of purifying the environment.
At present, the oxy-fuel combustion technology is widely applied to float glass and glass fiber kilns, the application of the oxy-fuel combustion technology in a cement kiln is in a research and development stage, and the oxy-fuel combustion technology is mainly adopted in a decomposing furnace and a rotary kiln.
Wherein, one scheme of adopting oxy-fuel combustion in the cement kiln is as follows:
the original cooler is divided into a first cooling area and a second cooling area, mixed gas of pure oxygen and carbon dioxide flue gas is introduced into the first cooling area to exchange heat with clinker, one part of the mixed gas after heat exchange enters the rotary kiln, the other part of the mixed gas enters the decomposing furnace to be combusted by fuel full oxygen in the rotary kiln and the decomposing furnace, conventional air is introduced into the second cooling area to exchange heat with the clinker, and the air after heat exchange is used for waste heat utilization or emission.
The above scheme has the following problems:
1. is led into the rotary kiln to form O2/CO2In the mixed gas O2The concentration is not easy to adjust, so that the flame temperature of the total oxygen combustion of the rotary kiln cannot be controlled, because the flame is introduced into the first-stage cooling area O2/CO2In the mixed gas O2The concentration is difficult to flexibly adjust in the actual production running process. The reason is that: o is2/CO2The mixed gas passes through the first cooling area of the cooler and then enters the rotary kiln for fuel combustion, and because the equipment structure and the grate bed area of the cooler are fixed and unchanged in the operation process, and the cooling air volume corresponding to the grate bed area of the first cooling area is relatively fixed, the O can be reduced if the circulating flue gas volume is increased2/CO2In the mixed gas O2Concentration, but the cooling air volume is increased, and the grate resistance is increased due to the increase of the cooling air volume; if the amount of the circulating flue gas is reduced, the O can be increased2/CO2In the mixed gas O2However, the concentration of clinker is reduced, and the reduction of the cooling air volume results in insufficient cooling of the clinker in the first cooling zone.
2. The temperature of combustion flame in the rotary kiln is too high, the lining is easy to damage, and especially when the thickness and direction of the flame are unstable in the combustion process, the high-temperature flame is easy to contact with the lining of the rotary kiln, so that the lining of the rotary kiln is damaged.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention provides a system and a method for producing cement clinker by using oxy-fuel combustion circulating preheating, which solve the problem that O is introduced into a rotary kiln in the oxy-fuel combustion technology of the prior cement kiln2/CO2O in the mixed gas2The concentration is not easy to adjust, thereby the flame temperature of the total oxygen combustion of the rotary kiln can not be controlled, and the combustion flame temperature in the rotary kiln is too high, so that the lining is easy to damage.
The invention is realized by the following technical scheme:
the invention relates to a system for producing cement clinker by using total oxygen combustion and cyclic preheating, which comprises a decomposing furnace, a smoke chamber, a rotary kiln and a cooler, wherein the rotary kiln is communicated with the cooler, and a combustor is arranged on the rotary kiln;
the preheater comprises a conventional preheater and a flue gas circulating preheater;
the cooler comprises a first cooling zone and a second cooling zone, the first cooling zone comprises a first cooling zone and a second cooling zone;
the inlet of the first cooling subarea is filled with a mixed gas of high-concentration pure oxygen and carbon dioxide flue gas, the outlet of the first cooling subarea is communicated with the air inlet of the rotary kiln, a first cooling gas is discharged from the outlet of the first cooling subarea and enters the air inlet of the rotary kiln as secondary air, and the first cooling gas is the mixed gas of the high-concentration pure oxygen and the carbon dioxide flue gas after heat exchange;
carbon dioxide flue gas is introduced into an inlet of the second cooling partition, an outlet of the second cooling partition is communicated with an air inlet of the rotary kiln through a first pipeline, second cooling gas is discharged from an outlet of the second cooling partition, the second cooling gas is controlled to enter the air inlet of the rotary kiln as fourth-time air, and the second cooling gas is carbon dioxide flue gas after heat exchange;
and air is introduced into an inlet of the second cooling area, third cooling gas is discharged from an outlet of the second cooling area, and the third cooling gas is air after heat exchange.
Further, an air inlet of the rotary kiln is provided with an air distribution cover;
introducing the first cooling gas entering the rotary kiln into the center of the inner side of the air distribution cover, so that the first cooling gas is distributed in the center area of the rotary kiln;
and introducing the second cooling gas entering the rotary kiln into the periphery of the air distribution cover, so that the second cooling gas is distributed in the peripheral area inside the rotary kiln.
Further, the burner is arranged at the center of the rotary kiln.
Further, the second cooling zone is disposed between the first cooling zone and the second cooling zone.
Furthermore, the cooler adopts a grate cooler, a roller crusher is arranged in the middle of the grate cooler, and the cooler is divided into a first cooling area and a second cooling area.
Furthermore, a partition wall is arranged in the middle of the first cooling area, and the first cooling area is divided into a first cooling subarea and a second cooling subarea.
Further, an air inlet at the bottom end of the conventional preheater is connected with an air outlet pipe of the decomposing furnace, and an air outlet at the top end of the conventional preheater discharges low-temperature flue gas; a feed inlet at the top end of the conventional preheater is used for raw material feeding, and a discharge outlet at the bottom end of the conventional preheater is communicated with the smoke chamber;
the low-temperature flue gas is discharged from a top end air outlet of the flue gas circulation preheater, a top end feed inlet of the flue gas circulation preheater is used for raw material feeding, and a bottom end discharge outlet of the flue gas circulation preheater is communicated with a bottom end air inlet pipe of the conventional preheater.
Furthermore, the outlet of the second cooling partition is communicated with the air inlet of the flue gas circulation preheater through a second pipeline, and part of second cooling gas discharged from the outlet of the second cooling partition is used for preheating the raw material of the flue gas circulation preheater.
Further, the outlet of the first cooling partition is communicated with the air inlet of the decomposing furnace through a tertiary air pipe;
and part of the first cooling gas discharged from the outlet of the first cooling subarea is used as tertiary air to enter the decomposing furnace for fuel combustion.
Further, the air outlet of the conventional preheater is connected with the first fan through a third pipeline, the flue gas at the air outlet of the first fan is divided into two paths, the first path of flue gas enters the waste gas treatment system through a fourth pipeline, the second path of flue gas enters a fifth pipeline provided with a second fan, and the flue gas at the outlet of the fifth pipeline is used as circulating flue gas to be mixed with high-concentration pure oxygen to form the mixed gas which enters the inlet of the first cooling subarea.
Furthermore, the air outlet of the conventional preheater is connected with the first fan through a third pipeline, the flue gas at the air outlet of the first fan is divided into two paths, the first path of flue gas enters the waste gas treatment system through a fourth pipeline, the second path of flue gas enters a fifth pipeline provided with a second fan, and the flue gas at the outlet of the fifth pipeline enters the inlet of the second cooling partition as circulating flue gas.
Furthermore, the air outlet of the conventional preheater is connected with the first fan through a third pipeline, the flue gas at the air outlet of the first fan is divided into two paths, the first path of flue gas enters the waste gas treatment system through a fourth pipeline, the second path of flue gas enters a fifth pipeline provided with a second fan, the flue gas at the outlet of the fifth pipeline is divided into two paths as circulating flue gas, the first path of circulating flue gas enters a sixth pipeline and is mixed with high-concentration pure oxygen to form the mixed gas which enters the inlet of the first cooling partition, and the second path of circulating flue gas enters the inlet of the second cooling partition through a seventh pipeline.
Further, a first heat exchanger is arranged on the third pipeline.
Furthermore, a dust collector is arranged at a position, close to an air inlet of the second fan, of the fifth pipeline.
Furthermore, an air outlet at the top end of the flue gas circulation preheater is connected with a fifth pipeline close to an inlet of the dust collector through an eighth pipeline provided with a second heat exchanger.
Further, a valve is arranged on the first pipeline.
The method for producing the cement clinker by adopting the system comprises the following steps:
raw materials are respectively fed into a conventional preheater and a flue gas circulating preheater, the raw materials are subjected to heat exchange separation with flue gas in the conventional preheater and the flue gas circulating preheater, and the preheated raw materials of the flue gas circulating preheater enter the bottom end of the conventional preheater and are mixed with the preheated raw materials of the conventional preheater to obtain mixed preheated raw materials;
the mixed preheated raw materials enter a decomposing furnace, and fuel in the decomposing furnace is combusted to release a large amount of heat for decomposing the raw materials to obtain hot raw materials;
the hot raw materials enter the rotary kiln through the smoke chamber, are calcined in the rotary kiln to form cement clinker, and the cement clinker enters the cooling machine from the outlet of the rotary kiln, and the concrete operation is as follows:
introducing mixed gas of high-concentration pure oxygen and carbon dioxide flue gas into a first cooling subarea to carry out primary cooling on the cement clinker to obtain first cooling gas and first cooled cement clinker;
the first cooling gas is used as secondary air to enter an air inlet of the rotary kiln, and the first cooling gas is mixed gas of high-concentration pure oxygen and carbon dioxide flue gas after heat exchange;
the first cooling cement clinker falls into a second cooling subarea, and carbon dioxide flue gas introduced into the second cooling subarea is used for carrying out secondary cooling on the first cooling cement clinker to obtain second cooling gas and second cooling cement clinker;
controlling the second cooling gas to enter an air inlet of the rotary kiln as four-time air, wherein the second cooling gas is carbon dioxide flue gas after heat exchange;
the second cooled cement clinker enters a second cooling area, and air in the second cooling area is introduced to carry out third cooling on the second cooled cement clinker to obtain a cement clinker finished product and third cooling gas, wherein the third cooling gas is air after heat exchange;
the kiln gas entering the decomposing furnace is mixed with the flue gas formed by fuel combustion and raw material decomposition in the decomposing furnace to obtain a mixed flue gas product, the mixed flue gas product enters the conventional preheater through the decomposing furnace, and is subjected to heat exchange separation with the raw material in the conventional preheater to form low-temperature flue gas, and the low-temperature flue gas is discharged from a top air outlet of the conventional preheater.
Further, the first cooling gas entering the rotary kiln is distributed in a central area of the rotary kiln, and the second cooling gas entering the rotary kiln is distributed in a peripheral area inside the rotary kiln.
Further, the low-temperature flue gas discharged from the top air outlet of the conventional preheater comprises the following three treatment routes:
the method comprises the following steps that low-temperature flue gas discharged from a conventional preheater enters a first fan, the flue gas at an air outlet of the first fan is divided into two paths, the first path of flue gas enters a waste gas treatment system, and the second path of flue gas passes through a second fan and then is used as circulating flue gas to be mixed with high-concentration pure oxygen to form a mixed gas which enters an inlet of a first cooling partition;
the low-temperature flue gas discharged from the conventional preheater enters a first fan, the flue gas at an air outlet of the first fan is divided into two paths, the first path of flue gas enters a waste gas treatment system, and the second path of flue gas passes through a second fan and then enters an inlet of a second cooling partition as circulating flue gas;
the low-temperature flue gas discharged from the conventional preheater enters a first fan, the flue gas at an air outlet of the first fan is divided into two paths, the first path of flue gas enters a waste gas treatment system, the second path of flue gas passes through a second fan and then is divided into two paths as circulating flue gas, the first path of circulating flue gas is mixed with high-concentration pure oxygen to form mixed gas which enters an inlet of a first cooling partition, and the second path of circulating flue gas enters an inlet of a second cooling partition.
Further, the first cooling gas also serves as tertiary air to enter the decomposing furnace for fuel combustion.
Furthermore, the second cooling gas also enters an air inlet of the flue gas circulation preheater to preheat raw materials of the flue gas circulation preheater.
Furthermore, low-temperature flue gas discharged from a conventional preheater firstly enters a first heat exchanger for heat exchange and utilization before entering a first fan.
And further, the second path of flue gas enters a dust collector for dust removal before entering a second fan.
Further, the low-temperature flue gas discharged from the flue gas circulating preheater is subjected to heat exchange and utilization by the second heat exchanger and then is mixed with the second path of flue gas before dust removal treatment.
Compared with the closest prior art, the technical scheme of the invention has the following beneficial effects:
the invention provides a system for producing cement clinker by using total oxygen combustion circulating preheating, which comprises a cooler, a first cooling area and a second cooling area, wherein the first cooling area comprises a first cooling subarea and a second cooling subarea, the mixed gas of high-concentration pure oxygen and carbon dioxide flue gas is introduced into the inlet of the first cooling subarea, the outlet of the first cooling subarea is communicated with the air inlet of a rotary kiln, the first cooling gas (the mixed gas of the high-concentration pure oxygen and the carbon dioxide flue gas after heat exchange) discharged from the outlet of the first cooling subarea is used as secondary air to enter the air inlet of the rotary kiln, the carbon dioxide flue gas is introduced into the inlet of the second cooling subarea, the outlet of the second cooling subarea is communicated with the air inlet of the rotary kiln through a first pipeline, and the second cooling gas (the carbon dioxide flue gas after heat exchange) discharged from the outlet of the second cooling subarea is controlled to enter the air inlet of the rotary kiln as four times of air, preferably by providing the first conduit withThe mode of the valve controls the second cooling gas (namely the carbon dioxide flue gas after heat exchange) discharged from the outlet of the second cooling subarea to enter the air inlet of the rotary kiln, so that the O in the mixed gas in the rotary kiln is adjusted2And the concentration, and then the temperature of the flame of the total oxygen combustion of the rotary kiln is controlled.
The air inlet of the rotary kiln is provided with the air distribution cover, the first cooling gas entering the rotary kiln is introduced into the center of the inner side of the air distribution cover, so that the first cooling gas is distributed in the center area of the rotary kiln, the second cooling gas entering the rotary kiln is introduced into the periphery of the air distribution cover, and the second cooling gas is distributed in the peripheral area inside the rotary kiln, so that a graded oxygen concentration distribution environment with low peripheral oxygen content and high central area oxygen content is formed in the rotary kiln, and therefore, under the condition that fuel is combusted in the center area of the rotary kiln in the full oxygen mode, the peripheral oxygen concentration of the rotary kiln is low, a low-oxygen-concentration inert gas protective layer is formed, high-temperature flame in the rotary kiln is prevented from diffusing to the periphery, the high-temperature flame is prevented from contacting with the wall surface of the rotary kiln, the lining of the rotary kiln is prevented from being burnt by the high-temperature flame, and the equipment safety under the full oxygen combustion of the cement kiln is improved. And preferably, the burner is inserted into the central position of the rotary kiln, so that the fuel is sprayed to the central area of the rotary kiln through the burner, high-temperature flame is formed in the central area through rapid combustion, and the high-temperature flame is further prevented from contacting with the wall surface of the rotary kiln.
The second cooling subarea which is introduced with the carbon dioxide flue gas is adopted to block air blow-by between the first cooling subarea and the second cooling subarea, so that the concentration of the carbon dioxide entering the first cooling subarea is prevented from being reduced, and the carbon enrichment effect of the cement production system is improved.
The outlet of the second cooling subarea is also communicated with the air inlet of the flue gas circulating preheater through a second pipeline, so that the high-temperature heat of the carbon dioxide flue gas after the cement clinker is cooled is used for heat exchange of raw materials in the flue gas circulating preheater, and the heat energy consumption of a cement production system is reduced.
Under the condition of oxy-fuel combustion, because nitrogen exists hardly, thermal NOx is hardly formed in the high-temperature combustion process of the rotary kiln. Meanwhile, after the flue gas is circulated, NOx in the circulating flue gas is regeneratedThe secondary entering system prolongs the reduction period of NOx, enhances the reduction effect and reduces the NOx emission. At the same time, SO in the circulating flue gas2Entering the kiln to react with CaO to produce sulfate, SO as to reduce SO in the waste gas2And (5) discharging.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
FIG. 1 is a schematic structural diagram of a system for producing cement clinker by preheating in an oxy-fuel combustion cycle according to the present invention;
FIG. 2 is a flow chart of a method for producing cement clinker by preheating with an oxy-fuel combustion cycle;
FIG. 3 is a partial schematic view of a rotary kiln according to the present invention;
fig. 4 is a side view of fig. 3.
Wherein, 1-smoke chamber, 2-rotary kiln, 201-burner, 202-wind distributing cover, 2021-positive wind inlet, 2022-tangential wind inlet, 3-cooler, 3011-first cooling subarea, 3012-second cooling subarea, 302-second cooling subarea, 4-decomposing furnace, 401-wind outlet pipe, 501-conventional preheater, 5011-first cyclone separator, 5012-second cyclone separator, 5013-third cyclone separator, 5014-fourth cyclone separator, 5015-fifth cyclone separator, 502-smoke circulating preheater, 5021-sixth cyclone separator, 5022-seventh cyclone separator, 5023-eighth cyclone separator, 5024-ninth cyclone separator, 601-first wind inlet pipe, 602-second wind inlet pipe, 603-a third air inlet pipe, 604-a fourth air inlet pipe, 605-a fifth air inlet pipe, 606-a sixth air inlet pipe, 607-a seventh air inlet pipe, 7-a communication pipeline, 8-a tertiary air pipe, 901-a first pipeline, 902-a second pipeline, 903-a third pipeline, 904-a fourth pipeline, 905-a fifth pipeline, 906-a sixth pipeline, 907-a seventh pipeline, 908-an eighth pipeline, 10-a valve, 11-a roller crusher, 12-a partition wall, 13-a first fan, 14-a second fan, 151-a first heat exchanger, 152-a second heat exchanger and 16-a dust collector.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments of the present invention, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on those shown in the drawings, and are used only for convenience in describing the present invention and for simplicity in description, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present invention. Furthermore, the terms "first", "second", etc. are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first," "second," etc. may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless otherwise specified.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; 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 by those of ordinary skill in the art through specific situations.
The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.
Referring to fig. 1, there is shown a schematic structural diagram of a system for producing cement clinker by oxy-fuel combustion cycle preheating in the present embodiment, wherein the dotted line with arrows is the air flow direction and the solid line with arrows is the material flow direction, and the system for producing cement clinker by oxy-fuel combustion cycle preheating comprises a smoke chamber 1, a rotary kiln 2, a cooler 3 and a raw meal preheating pre-decomposition system.
The raw material preheating and predecomposition system is communicated with the smoke chamber 1, the rotary kiln 2 is provided with a burner 201, fuel F is introduced into the burner 201, the tail part of the rotary kiln 2 is communicated with the smoke chamber 1, and the head part of the rotary kiln 2 is communicated with the cooler 1.
The raw meal preheating pre-decomposition system comprises a decomposing furnace 4 and a preheater, the preheater comprises a conventional preheater 501 and a flue gas circulating preheater 502, the preheater is preferably a cyclone preheater, the conventional preheater 501 illustrated in the figure is a cyclone preheater, the flue gas circulating preheater 502 is a cyclone preheater, and the conventional preheater 501 and the flue gas circulating preheater 502 only adopt 1 column of cyclone preheaters, it needs to be explained that the column numbers of the conventional preheater 501 and the flue gas circulating preheater 502 in the figure are only illustrated, and the skilled person can set according to actual needs.
The decomposing furnace 4 is provided with a burner, fuel F is introduced into the burner, the side wall of the decomposing furnace 4 is provided with a raw material inlet, the top of the decomposing furnace 4 is provided with an air outlet pipe 401, and it should be noted that the air outlet pipe 401 can also be arranged on the side surface of the decomposing furnace 4.
The air inlet at the bottom end of the conventional preheater 501 is connected with the air outlet pipe 401 of the decomposing furnace 4, the air outlet at the top end of the conventional preheater 501 discharges low-temperature flue gas, the top end feed inlet of the conventional preheater 501 is used for feeding raw material R, the bottom end discharge outlet of the conventional preheater 501 is communicated with the smoke chamber 1, and specifically, the conventional preheater 501 is illustrated in the figure to comprise a first cyclone separator 5011, a second cyclone separator 5012, a third cyclone separator 5013, a fourth cyclone separator 5014 and a fifth cyclone separator 5015 which are sequentially communicated, it is to be noted that the number of the conventional separators 501 in the figure is only illustrated, and a person skilled in the art can set the number as required.
The top end of the first cyclone separator 5011 is provided with an air outlet, the air outlet discharges low-temperature flue gas, the side face of the top end of the first cyclone separator 5011 is communicated with the first air inlet pipe 601, the first air inlet pipe 5011 is provided with a feed inlet, the feed inlet is used for raw material feeding, and the bottom end of the first cyclone separator 5011 is communicated with the second air inlet pipe 602.
The top end of the second cyclone 5012 is communicated with the first air inlet pipe 601, the side face of the top end of the second cyclone 5012 is communicated with the second air inlet pipe 602, and the bottom end of the second cyclone 5012 is communicated with the third air inlet pipe 603.
The top end of the third cyclone 5013 is communicated with the second air inlet pipe 602, the side surface of the top end of the third cyclone 5013 is communicated with the third air inlet pipe 603, and the bottom end of the third cyclone 5013 is communicated with the fourth air inlet pipe 604.
The top end of the fourth cyclone 5014 is communicated with the third air inlet pipe 603, the side surface of the top end of the fourth cyclone 5014 is communicated with the fourth air inlet pipe 604, and the bottom end of the fourth cyclone 5014 is communicated with the raw meal inlet of the decomposing furnace 4.
The top end of the fifth cyclone separator 5015 is communicated with the fourth air inlet pipe 604, the side face of the top end of the fifth cyclone separator 5015 is provided with an air inlet, the air inlet is communicated with the air outlet pipe 401 of the decomposing furnace 4 through a communicating pipeline 7, the bottom end of the fifth cyclone separator 5015 is provided with a discharge hole, and the discharge hole is communicated with the smoke chamber 1.
The top end air outlet of the flue gas circulation preheater 502 discharges low-temperature flue gas, the top end feed inlet of the flue gas circulation preheater 502 is used for raw material feeding, the bottom end discharge outlet of the flue gas circulation preheater 502 is communicated with the bottom end air inlet pipe of the conventional preheater 501, the stage number of the flue gas circulation preheater 502 is 2-5 stages, specifically, the flue gas circulation preheater 502 in the figure comprises a sixth cyclone 5021, a seventh cyclone 5022, an eighth cyclone 5023 and a ninth cyclone 5024, it needs to be explained that the number of the flue gas circulation preheater 502 in the figure is only schematic, and the skilled person in the art can set the number as required.
An air outlet is formed in the top end of the sixth cyclone 5021, low-temperature smoke is discharged from the air outlet, the side face of the top end of the sixth cyclone 5021 is communicated with the fifth air inlet pipe 605, a feed inlet is formed in the fifth air inlet pipe 605 and used for feeding raw materials, and the bottom end of the sixth cyclone 5021 is communicated with the sixth air inlet pipe 606.
The top end of the seventh cyclone 5022 is communicated with the fifth air inlet pipe 605, the side face of the top end of the seventh cyclone 5022 is communicated with the sixth air inlet pipe 606, and the bottom end of the seventh cyclone 5022 is communicated with the seventh air inlet pipe 607.
The top end of the eighth cyclone 5023 is communicated with the sixth air inlet pipe 606, the side face of the top end of the eighth cyclone 5023 is communicated with the seventh air inlet pipe 607, and the bottom end of the eighth cyclone 5023 is communicated with the air inlet on the side face of the top end of the ninth cyclone 5024.
The top end of the ninth cyclone 5024 is communicated with the seventh air inlet pipe 607, and the bottom end of the ninth cyclone 5024 is communicated with the bottom air inlet pipe of the conventional preheater 501, i.e., the fourth air inlet pipe 604.
The cooler 3 is a grate cooler, the roller crusher 11 is arranged in the middle of the grate cooler, the cooler 3 is divided into a first cooling area and a second cooling area 302, the partition wall 12 is arranged in the middle of the first cooling area, the first cooling area is divided into a first cooling sub-area 3011 and a second cooling sub-area 3012, and the second cooling sub-area 3012 is arranged between the first cooling sub-area 3011 and the second cooling area 302.
The mixed gas of high-concentration pure oxygen A and carbon dioxide flue gas is introduced into an inlet of the first cooling subarea 3011, the oxygen concentration in the mixed gas is 50-98%, the carbon dioxide flue gas B is introduced into an inlet of the second cooling subarea 3012, the oxygen concentration in the carbon dioxide flue gas B is lower than 10%, air C is introduced into an inlet of the second cooling subarea 302, an output source of the air can be a fan, the pure oxygen can be prepared by an oxygen preparation system or purchased, and the optimal pure oxygen purity interval is 85-98%.
With cooler 3 adoption above-mentioned subregion setting, can block the air between first cooling zone 3011 and the second cooling zone 3012 and scurry wind to avoid getting into the reduction of the carbon dioxide concentration of first cooling zone 3011, and then promote the carbon enrichment effect of cement production system.
As a preferred embodiment, the outlet of the first cooling sub-zone 3011 discharges a first cooling gas, the first cooling gas is a mixed gas of high-concentration pure oxygen and carbon dioxide flue gas after heat exchange, the first cooling gas is divided into two paths, the first cooling gas g1 in the first path is used as secondary air to directly enter the rotary kiln 2 for fuel combustion, and the first cooling gas g2 in the second path is used as tertiary air to enter the decomposing furnace 4 through the tertiary air duct 8 for fuel combustion.
The outlet of the second cooling subarea 3012 discharges second cooling gas, the second cooling gas is carbon dioxide flue gas after heat exchange, the second cooling gas is divided into two paths, the second cooling gas g31 of the first path is used as four-time air to enter the air inlet of the rotary kiln through the first pipeline 901, a valve 10 is arranged on the first pipeline 901, the amount of the second cooling gas entering the rotary kiln is adjusted through the valve 10, and therefore the amount of the second cooling gas entering the rotary kiln is adjusted, and O in the mixed gas in the rotary kiln is adjusted2And the concentration, and then the temperature of the flame of the total oxygen combustion of the rotary kiln is controlled. The second cooling gas g32 of the second path enters the air inlet of the flue gas circulation preheater 502 through the second pipeline 902, that is, enters the air inlet of the ninth cyclone 5024, so that the high-temperature heat of the carbon dioxide flue gas after cooling the cement clinker is used for heat exchange of raw materials in the flue gas circulation preheater, thereby reducing the heat energy consumption of the cement production system.
And a third cooling gas g4 is discharged from an outlet of the second cooling area 302, the third cooling gas g4 is air after heat exchange, and the temperature of the third cooling gas g4 is 200-300 ℃, and the third cooling gas g4 is used as a drying heat source of the raw material and fuel grinding system, so that the heat source generated by the cement production system is further fully utilized, and the cement clinker is cooled by the second cooling area 302 to obtain a cement clinker finished product K.
As shown in fig. 3-4, as a preferred embodiment, a wind inlet of the rotary kiln 2 is provided with a wind distribution hood 202, the first cooling gas is introduced into the central position inside the wind distribution hood 202, i.e. the first cooling gas enters along a forward wind inlet 2021 of the wind distribution hood 202, so that the first cooling gas is distributed in the central area of the rotary kiln 2, the second cooling gas is introduced into the periphery of the wind distribution hood 202, i.e. the second cooling gas enters along a tangential wind inlet 2022 of the wind distribution hood 202, so that the second cooling gas is distributed in the peripheral area inside the rotary kiln 2, thereby forming a graded oxygen concentration distribution environment with low peripheral oxygen content and high central area oxygen content in the rotary kiln 2, so as to realize the total oxygen combustion of the fuel in the central area of the rotary kiln 2, the peripheral oxygen concentration of the rotary kiln 2 is low, a low-oxygen-concentration inert gas protective layer is formed, and the diffusion of high-temperature flame in the rotary kiln 2 to the periphery is hindered, the high-temperature flame is prevented from contacting the wall surface of the rotary kiln 2, so that the lining of the rotary kiln 2 is prevented from being burnt by the high-temperature flame, and the safety of equipment under the full-oxygen combustion of the cement kiln is improved. And it is preferable that the burner 201 is inserted into the central position of the rotary kiln 2, so as to ensure that the fuel is injected into the central area of the rotary kiln 2 through the burner, and the high temperature flame is formed by rapid combustion in the central area, thereby further preventing the high temperature flame from contacting the wall surface of the rotary kiln 2.
As a preferred embodiment, in order to fully utilize the flue gas at the outlet of the conventional preheater 501, the air outlet of the conventional preheater 501 is connected to the first fan 13 through the third pipeline 903, that is, the air outlet of the first cyclone separator 501 in the figure is connected to the first fan 13 through the third pipeline 903, the flue gas at the air outlet of the first fan 13 is divided into two paths, the first path of flue gas D enters the waste gas treatment system through the fourth pipeline 904, the second path of flue gas enters the fifth pipeline 905 provided with the second fan 14, and the flue gas (the content of carbon dioxide in the flue gas is greater than 70) at the outlet of the fifth pipeline 905 is treated by the following three schemes:
scheme 1: the flue gas from the outlet of the fifth pipeline 905 is used as circulating flue gas and mixed with pure oxygen to form the mixed gas, and the mixed gas enters the inlet of the first cooling partition 3011.
Scheme 2: the flue gas from the outlet of the fifth duct 905 enters the inlet of the second cooling zone 3012 as recycled flue gas.
Scheme 3: the flue gas at the outlet of the fifth pipeline 905 is divided into two paths as the circulating flue gas, the first path of circulating flue gas enters the sixth pipeline 906 to be mixed with pure oxygen to form the mixed gas which enters the inlet of the first cooling subarea 3011, and the second path of circulating flue gas enters the inlet of the second cooling subarea 3012 through the seventh pipeline 907.
The first fan 13 is a high temperature fan, and the second fan 14 is a circulating fan.
Since the flue gas exhausted from the air outlet of the conventional preheater 501 needs to be used as a cooling medium to enter the cooling machine 3, in order to avoid the over-high temperature of the flue gas from being harmful to the cooling of the clinker in the cooling machine 3, as a preferred embodiment, the first heat exchanger 151 is arranged on the third pipeline 903, so that the temperature of the flue gas at the outlet of the first heat exchanger 151 is reduced to below 100 ℃, and preferably, the first heat exchanger 151 can be a waste heat power generation boiler or an air heat exchanger.
The flue gas entering the second fan 14 may have a high dust content, and if the dust content is high, on one hand, the dust is easy to settle in the fifth pipeline 905 between the second fan 14 and the cooling machine 1 to form accumulated material, which increases the pipeline resistance, and on the other hand, the high dust content increases the abrasion of the second fan 14. Therefore, as a preferred embodiment, the fifth pipeline 905 is provided with a dust collector 16 at a position close to the air inlet of the second fan 14, so as to perform dust removal treatment on the flue gas entering the second fan 14 in advance, thereby reducing the dust concentration in the second fan 14 to 100mg/m3The following.
As a preferred embodiment, a valve 10 is arranged on the fifth pipeline 905, so that the circulating quantity of the flue gas can be conveniently adjusted, and the temperature of the gas at the outlet of the second cooling subarea 3012 is controlled to be 600-;
a valve 10 is arranged on the sixth pipeline 906, so that the concentration of oxygen in the pure oxygen and carbon dioxide mixed gas can be conveniently adjusted;
a valve 10 is provided in the second conduit 902 to facilitate regulation of the amount of second cooling gas entering the preheater.
In a preferred embodiment, the air outlet of the flue gas circulation preheater 502 is connected with the fifth pipeline 905 close to the inlet of the dust collector 16 through the eighth pipeline 908 of the second heat exchanger 152, so that the low-temperature flue gas discharged from the air outlet of the flue gas circulation preheater 502 can be continuously introduced into the cooler 3 as the high-concentration carbon dioxide circulation flue gas, and the second heat exchanger 152 can cool the flue gas at the air outlet of the flue gas circulation preheater 502, thereby facilitating the cooling of clinker in the cooler.
Referring to fig. 2, a flow chart of a method for producing cement clinker by using the system is shown, wherein a dotted arrow line is an air flow direction, and a solid arrow line is a material flow direction, and the method for preparing cement clinker by using the system comprises the following steps:
i-1, respectively feeding raw meal R into a conventional preheater 501 and a flue gas circulating preheater 502, carrying out heat exchange separation on the raw meal R and flue gas in the conventional preheater 501 and the flue gas circulating preheater 502, feeding the preheated raw meal of the flue gas circulating preheater 502 into the bottom end of the conventional preheater 501, and mixing the preheated raw meal with the preheated raw meal of the conventional preheater 501 to obtain mixed preheated raw meal;
i-2, mixing and preheating the raw materials, feeding the mixed and preheated raw materials into a decomposing furnace 4, and burning the fuel in the decomposing furnace 4 to release a large amount of heat for decomposing the raw materials to obtain hot raw materials;
i-3 hot raw materials enter the rotary kiln 2 through the smoke chamber, and are calcined in the rotary kiln 2 to form cement clinker K1 (as shown in figure 4), wherein the temperature of the cement clinker K1 is 1300-:
introducing a mixed gas of high-concentration pure oxygen A and carbon dioxide flue gas B into the first cooling subarea 3011 to cool the cement clinker for the first time to obtain a first cooling gas and a first cooled cement clinker;
the temperature of the first cooling gas is 900-1300 ℃, the first cooling gas is divided into two paths, the first cooling gas g1 serving as secondary air enters along the forward air inlet 2021 of the air distribution hood 202, so that the first cooling gas g1 is distributed in the central area of the rotary kiln 2 and is used for the combustion of the fuel in the rotary kiln 2, kiln gas formed by the combustion of the fuel in the rotary kiln 2 and the decomposition of part of raw materials enters the decomposing furnace 4, and the first cooling gas g2 serving as the tertiary air enters the decomposing furnace 4 and is used for the combustion of the fuel;
the first cooling cement clinker falls into a second cooling subarea 3012, and the carbon dioxide flue gas introduced into the second cooling subarea 3012 is used for carrying out secondary cooling on the first cooling cement clinker to obtain a second cooling gas and a second cooling cement clinker;
the temperature of the second cooling gas is 600-; the second path of the second cooling gas g32 enters the air inlet of the flue gas circulation preheater 502;
the second cooled cement clinker enters a second cooling area 302, and air C introduced into the second cooling area 302 is used for carrying out third cooling on the second cooled cement clinker to obtain a cement clinker finished product K and third cooling gas g4, wherein the temperature of the cement clinker finished product K is about 100 ℃;
the third cooling gas g4 is used as a drying heat source of the raw material and fuel grinding system;
i-4, mixing the kiln gas entering the decomposing furnace 4 with the flue gas formed by fuel combustion and raw material decomposition in the decomposing furnace 4 to obtain a mixed flue gas product, enabling the mixed flue gas product to enter the conventional preheater 501 through the air outlet pipe of the decomposing furnace 4, performing heat exchange separation with the raw material in the conventional preheater 501 to obtain low-temperature flue gas, discharging the low-temperature flue gas from the top air outlet of the conventional preheater 501, and discharging CO in the low-temperature flue gas2The concentration is 70-95%;
i-5 low-temperature flue gas (the content of carbon dioxide in the flue gas is 70-95%) discharged from a conventional preheater 501 enters a first fan 13 after heat exchange through a heat exchanger 151, the flue gas at an air outlet of the first fan 13 is divided into two paths, the first path of flue gas D enters a waste gas treatment system, and the second path of flue gas is processed by the following three schemes:
1. the second path of flue gas enters a dust collector 16 for dust removal treatment, and is mixed with pure oxygen as circulating flue gas after passing through a second fan 14 to form mixed gas, and the mixed gas enters an inlet of the first cooling subarea 3011;
2. the second path of flue gas enters a dust collector 16 for dust removal treatment, passes through a second fan 14 and then enters an inlet of a second cooling subarea 3012 as circulating flue gas;
3. the second flue gas enters the dust collector 16 for dust removal treatment, and is divided into two paths as circulating flue gas after passing through the second fan 14, the first path of circulating flue gas is mixed with high-concentration pure oxygen to form the mixed gas, and the mixed gas enters the inlet of the first cooling partition 3011, and the second path of circulating flue gas enters the inlet of the second cooling partition 3012 (fig. 2 shows the flow of the scheme).
I-6, the low-temperature flue gas (the content of carbon dioxide in the flue gas is 70-95%) discharged from the air outlet of the flue gas circulating preheater 502 is subjected to heat exchange by the second heat exchanger 152 and then is mixed with the second path of flue gas before dust removal treatment.
Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art can make modifications and equivalents to the embodiments of the present invention without departing from the spirit and scope of the present invention, which is set forth in the claims of the present application.

Claims (24)

1. A system for producing cement clinker by using oxy-fuel combustion and circulating preheating comprises a decomposing furnace, a preheater, a smoke chamber, a rotary kiln and a cooler, wherein the rotary kiln is communicated with the cooler, and a combustor is arranged on the rotary kiln; it is characterized in that the preparation method is characterized in that,
the preheater comprises a conventional preheater and a flue gas circulating preheater;
the air inlet of the rotary kiln is provided with an air distribution cover, and the air distribution cover is provided with a forward air inlet and a tangential air inlet;
the cooler comprises a first cooling zone and a second cooling zone, the first cooling zone comprises a first cooling zone and a second cooling zone;
the inlet of the first cooling subarea is filled with a mixed gas of high-concentration pure oxygen and carbon dioxide flue gas, the outlet of the first cooling subarea is communicated with the air inlet of the rotary kiln, a first cooling gas is discharged from the outlet of the first cooling subarea and enters the air inlet of the rotary kiln as secondary air, and the first cooling gas is the mixed gas of the high-concentration pure oxygen and the carbon dioxide flue gas after heat exchange;
carbon dioxide flue gas is introduced into an inlet of the second cooling partition, an outlet of the second cooling partition is communicated with an air inlet of the rotary kiln through a first pipeline, second cooling gas is discharged from an outlet of the second cooling partition, the second cooling gas is controlled to enter the air inlet of the rotary kiln as fourth-time air, and the second cooling gas is carbon dioxide flue gas after heat exchange;
and air is introduced into an inlet of the second cooling area, third cooling gas is discharged from an outlet of the second cooling area, and the third cooling gas is air subjected to heat exchange.
2. The system for producing cement clinker by preheating in oxy-fuel combustion cycle as recited in claim 1,
introducing the first cooling gas entering the rotary kiln into the center of the inner side of the air distribution cover, so that the first cooling gas is distributed in the center area of the rotary kiln;
and introducing the second cooling gas entering the rotary kiln into the periphery of the air distribution cover, so that the second cooling gas is distributed in the peripheral area inside the rotary kiln.
3. The system for producing cement clinker by oxy-fuel combustion cycle preheating as recited in claim 1, wherein said burner is disposed at a central position of the rotary kiln.
4. The system for producing cement clinker by oxy-fuel combustion cycle preheating according to claim 1, wherein the second cooling zone is provided between the first cooling zone and the second cooling zone.
5. The system for producing the cement clinker by the preheating of the oxy-fuel combustion cycle as recited in claim 1, wherein the cooler is a grate cooler, a roller crusher is arranged in the middle of the grate cooler, and the grate cooler is divided into a first cooling area and a second cooling area.
6. The system for pre-heating cement clinker according to claim 1, wherein a partition wall is disposed in the middle of the first cooling zone to divide the first cooling zone into a first cooling zone and a second cooling zone.
7. The system for producing cement clinker by preheating through oxy-fuel combustion cycle as recited in claim 1, wherein the air inlet at the bottom end of the conventional preheater is connected with the air outlet pipe of the decomposing furnace, and the air outlet at the top end of the conventional preheater discharges low-temperature flue gas; a feed inlet at the top end of the conventional preheater is used for raw material feeding, and a discharge outlet at the bottom end of the conventional preheater is communicated with the smoke chamber;
the low-temperature flue gas is discharged from a top end air outlet of the flue gas circulation preheater, a top end feed inlet of the flue gas circulation preheater is used for raw material feeding, and a bottom end discharge outlet of the flue gas circulation preheater is communicated with a bottom end air inlet pipe of the conventional preheater.
8. The system for producing cement clinker by preheating in oxy-fuel combustion cycle as recited in claim 1,
and the outlet of the second cooling subarea is also communicated with the air inlet of the flue gas circulating preheater through a second pipeline, and part of second cooling gas discharged from the outlet of the second cooling subarea preheats the raw material of the flue gas circulating preheater.
9. The system for producing cement clinker by using oxy-fuel combustion cyclic preheating as recited in claim 1, wherein the outlet of the first cooling zone is further communicated with the air inlet of the decomposing furnace through a tertiary air pipe;
and part of the first cooling gas discharged from the outlet of the first cooling subarea is used as tertiary air to enter the decomposing furnace for fuel combustion.
10. The system for producing cement clinker by using total oxygen combustion circulating preheating as claimed in claim 1, wherein the air outlet of the conventional preheater is connected with a first fan through a third pipeline, the flue gas at the air outlet of the first fan is divided into two paths, the first path of flue gas enters the waste gas treatment system through a fourth pipeline, the second path of flue gas enters a fifth pipeline provided with a second fan, and the flue gas at the outlet of the fifth pipeline is mixed with high-concentration pure oxygen as circulating flue gas to form the mixed gas which enters the inlet of the first cooling subarea.
11. The system for producing cement clinker by using the total oxygen combustion circulating preheating as claimed in claim 1, wherein the air outlet of the conventional preheater is connected with a first fan through a third pipeline, the flue gas at the air outlet of the first fan is divided into two paths, the first path of flue gas enters the waste gas treatment system through a fourth pipeline, the second path of flue gas enters a fifth pipeline provided with a second fan, and the flue gas at the outlet of the fifth pipeline enters the inlet of the second cooling subarea as circulating flue gas.
12. The system for producing cement clinker through total oxygen combustion cyclic preheating according to claim 1, wherein the air outlet of the conventional preheater is connected with a first fan through a third pipeline, the flue gas at the air outlet of the first fan is divided into two paths, the first path of flue gas enters the waste gas treatment system through a fourth pipeline, the second path of flue gas enters a fifth pipeline provided with a second fan, the flue gas at the outlet of the fifth pipeline is divided into two paths as circulating flue gas, the first path of circulating flue gas enters a sixth pipeline and is mixed with high-concentration pure oxygen to form the mixed gas which enters the inlet of the first cooling subarea, and the second path of circulating flue gas enters the inlet of the second cooling subarea through a seventh pipeline.
13. The oxy-fuel combustion cycle preheating cement clinker production system as recited in any one of claims 10 to 12, wherein said third conduit is provided with a first heat exchanger.
14. The oxy-fuel combustion cycle preheating cement clinker production system as recited in any one of claims 10 to 12, wherein said fifth pipeline is provided with a dust collector at a position close to an air inlet of said second fan.
15. The system for producing the cement clinker by the preheating of the oxy-fuel combustion cycle as recited in claim 1, wherein the air outlet at the top end of the flue gas cycle preheater is connected with the fifth pipeline at a position close to the inlet of the dust collector through an eighth pipeline provided with the second heat exchanger.
16. The system for producing cement clinker by preheating in oxy-fuel combustion cycle as recited in claim 1,
and a valve is arranged on the first pipeline.
17. A method for producing cement clinker using the system of claim 1, comprising the steps of:
raw materials are respectively fed into a conventional preheater and a flue gas circulating preheater, the raw materials are subjected to heat exchange separation with flue gas in the conventional preheater and the flue gas circulating preheater, and the preheated raw materials of the flue gas circulating preheater enter the bottom end of the conventional preheater and are mixed with the preheated raw materials of the conventional preheater to obtain mixed preheated raw materials;
the mixed preheated raw materials enter a decomposing furnace, and fuel in the decomposing furnace is combusted to release a large amount of heat for decomposing the raw materials to obtain hot raw materials;
the hot raw materials enter the rotary kiln through the smoke chamber, are calcined in the rotary kiln to form cement clinker, and the cement clinker enters the cooling machine from the outlet of the rotary kiln, and the concrete operation is as follows:
introducing a mixed gas of high-concentration pure oxygen and carbon dioxide flue gas into a first cooling subarea to carry out primary cooling on the cement clinker to obtain a first cooling gas and a first cooled cement clinker;
the first cooling gas is used as secondary air and enters the air inlet of the rotary kiln along the positive air inlet of the air distribution cover, and the first cooling gas is a mixed gas of high-concentration pure oxygen and carbon dioxide flue gas after heat exchange;
the first cooling cement clinker falls into a second cooling subarea, and carbon dioxide flue gas introduced into the second cooling subarea is used for carrying out secondary cooling on the first cooling cement clinker to obtain second cooling gas and second cooling cement clinker;
controlling the second cooling gas as four-time air to enter the air inlet of the rotary kiln along the tangential air inlet of the air distribution cover, wherein the second cooling gas is carbon dioxide flue gas after heat exchange;
the second cooled cement clinker enters a second cooling area, and air in the second cooling area is introduced to carry out third cooling on the second cooled cement clinker to obtain a cement clinker finished product and third cooling gas, wherein the third cooling gas is air after heat exchange;
the kiln gas entering the decomposing furnace is mixed with the flue gas formed by fuel combustion and raw material decomposition in the decomposing furnace to obtain a mixed flue gas product, the mixed flue gas product enters the conventional preheater through the decomposing furnace, and is subjected to heat exchange separation with the raw material in the conventional preheater to form low-temperature flue gas, and the low-temperature flue gas is discharged from a top air outlet of the conventional preheater.
18. A method for producing cement clinker according to claim 17, wherein the first cooling gas entering the rotary kiln is distributed in a central region of the rotary kiln and the second cooling gas entering the rotary kiln is distributed in a peripheral region inside the rotary kiln.
19. The method for producing cement clinker according to claim 17, wherein the low temperature flue gas discharged from the top outlet of the conventional preheater comprises three processing routes:
the method comprises the following steps that low-temperature flue gas discharged from a conventional preheater enters a first fan, the flue gas at an air outlet of the first fan is divided into two paths, the first path of flue gas enters a waste gas treatment system, and the second path of flue gas passes through a second fan and then is used as circulating flue gas to be mixed with high-concentration pure oxygen to form a mixed gas which enters an inlet of a first cooling subarea;
the low-temperature flue gas discharged from the conventional preheater enters a first fan, the flue gas at an air outlet of the first fan is divided into two paths, the first path of flue gas enters a waste gas treatment system, and the second path of flue gas passes through a second fan and then enters an inlet of a second cooling partition as circulating flue gas;
the low-temperature flue gas discharged from the conventional preheater enters a first fan, the flue gas at an air outlet of the first fan is divided into two paths, the first path of flue gas enters a waste gas treatment system, the second path of flue gas passes through a second fan and then is divided into two paths as circulating flue gas, the first path of circulating flue gas is mixed with high-concentration pure oxygen to form mixed gas which enters an inlet of a first cooling partition, and the second path of circulating flue gas enters an inlet of a second cooling partition.
20. The method for producing cement clinker of claim 17, wherein the primary cooling gas is also fed as tertiary air into the decomposition furnace for fuel combustion.
21. The method for producing cement clinker according to claim 17, wherein the second cooling gas is also fed into the air inlet of the flue gas recirculation preheater to preheat the raw meal of the flue gas recirculation preheater.
22. The method for producing cement clinker according to claim 19, wherein the low temperature flue gas discharged from the conventional preheater enters the first heat exchanger for heat exchange before entering the first fan.
23. The method for producing cement clinker according to claim 19, wherein the second flue gas enters a dust collector for dust removal before entering the second fan.
24. The method for producing cement clinker according to claim 23, wherein the low temperature flue gas discharged from the flue gas circulating preheater is mixed with the second flue gas before the dedusting treatment after being subjected to heat exchange by the second heat exchanger.
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