KR960006221B1 - Process for the calcining of cement - Google Patents

Abstract

A plasticization apparatus is positioned between a suspension type pre-heater for pre-heating granular or powdered raw material of cement, etc. and a rotary plasticizer furnace for plasticizing decarboxylated raw material with the purpose of producing clinker. The apparatus inflows hot air for combustion from a cooler, and burns fuel separately with the rotary plasticizer furnace, to decarboxylate the fuel pre-heated by the suspension type pre-heater.

Description

Plasticizer of Cement Raw Material Using Internal Circulation

1 is a schematic diagram of a heat treatment apparatus for cement raw material for practicing the present invention.

2 is a schematic diagram showing an enlarged peripheral portion of the plasticizer of FIG.

FIG. 2 (a) is a schematic diagram showing an enlarged bottom of the plasticizer in FIG.

Fig. 2 (b) or Fig. 2 (a) is a plan view schematically showing the inside of the lower part of the furnace by cutting along line A-A in Fig. 2 (a).

3 is a schematic view showing another example of a thermal treatment apparatus for cement raw material for practicing the present invention.

4 is a schematic view showing an enlarged peripheral portion of the plasticizer in FIG.

5 is a schematic view of a conventional thermal treatment apparatus for cement raw materials.

* Explanation of the symbols for the main copies of the drawings

1: rotary kiln 2: cooler

3: plasticizer 3a: plasticizer upper part

3b: bottom of the gas furnace 4, 4a, 4b, 17, 18: combustion air supply conduit

5: tamper 6: draft tube

6a: Inside the draft tube 6b: Annulus area

7: flue gas conduit 8, 8a, 8b: raw material input conduit

9: Raw material inlet 11, 11 ', 19: Burner

12 duct 13 nozzle

14, 16: discharge conduit 15: mixing chamber

C1, C2, C3, C4, C5: Cyclone

The present invention relates to a plasticizer for cement raw materials using internal circulation. More specifically, the suspension preheater is placed between a suspension preheater and a rotary firing furnace for preheating granular or powdery raw materials such as cement, and the raw material is decarbonated while having a separate heat source and then fired in a rotary firing furnace. The present invention relates to a plasticizer for making a clinker and cooling it in a cooler to decarbonize powdered raw materials in the process of producing a cement clinker.

The method for producing the cement clinker can be divided into the use of a rotary firing furnace and the fluidized bed kiln according to the method of firing the decarbonized raw material.

In the conventional cement clinker manufacturing method using a rotary firing furnace, while preheating the powdery raw material in the suspension type preheater, decarburizing about 40% of the raw material, and injecting the rotary firing furnace into a rotary firing furnace to produce a clinker. However, in this method, the decarbonation reaction of raw materials, which take up a large part of the heat required for cement clinker production, occurs about 60% in the rotary kiln, so the heat load in the rotary kiln increases, which shortens the life of refractory lead and the kiln when mass production. There was a disadvantage in that the driving cost increases.

In order to solve this problem, the fuel was supplied to the lower part of the suspension preheater separately from the rotary kiln in an effort to decarbonize as much as possible before inputting the raw materials to the rotary kiln. Commercially available plasticizers used in the cement clinker manufacturing process usually have separate devices for burning fuel and decarbonizing raw materials. The types of plasticizers can be divided into fluidized bed and jet-sorted bed. have.

The jet-classifying layer is formed between the suspension type preheater and the rotary firing furnace according to the installation location of the firing furnace to form a splitting layer by the high temperature (900-1100 ° C) exhaust gas ejected from the rotary firing furnace. Formation of vortex by high temperature (700 ~ 900 ℃) oxygen-containing gas from cooler introduced in tangential or perpendicular direction and burning fuel by this mixed gas (Japanese Patent Laid-Open No. 53-134,028, Japanese Patent Nos. 54-90,228, Japanese Special Publication 59-32,176, Korean Special Publication No. 87-1568), independent suspension type preheater, not installed on rotary kiln, classified by hot oxygen-containing gas from cooler Formation of layers and combustion of fuel occurs (US Pat. No. 4,045,162, US Pat. No. 4,561,842).

Another type of calcining furnace decarbonizes raw materials while burning fuel by hot oxygen-containing gas from a cooler in a cyclone-type swinging furnace, and mixes the combustion exhaust gas and the raw materials and unburned fuel from the swinging furnace. In a chamber, high temperature (900-1100 ° C.) rotary firing is mixed with exhaust gas to further burn and decarbonize (US Pat. No. 3,834,860).

The invention is described in more detail with reference to the drawings as follows. 5 shows an embodiment of U.S. Patent No. 3,834,860, which is divided into a turning gas furnace 3 and a mixing chamber 15, and the turning gas furnace 3 contains oxygen from the cooler 2. There is a means for introducing gas and a means for introducing raw materials and unburned fuel discharged from the slewing furnace 3 into the mixing chamber 15, and the mixing chamber 15 has a high temperature exhaust gas from the rotary firing furnace 1. The means for introducing the gas and the means for introducing the flue-gas and the decarbonation source into the lowest cyclone are connected.

The high temperature oxygen-containing gas from the cooler 2 is introduced tangentially into the swirling gas path 3 to form swirl flow. The preheated raw material in the suspension type preheater is decarbonized by the heat of combustion of the fuel while descending along the furnace wall surface while turning in the turning gas furnace 3 by the oxygen-containing gas from the cooler 2 introduced in the tangential direction. The fuel injected into the swirl flow in the upper portion of the turning plastic furnace 3 is characterized by forming a flame in the center of the furnace. Unburned fuel moves down the wall of the furnace by centrifugal force of swirling flow with the raw materials and descends to the mixing chamber.

The combustion flue gas from the swinging calciner 3 also moves to the mixing chamber together with the solid particles. The fuel and raw materials supplied to the mixing chamber are further combusted and decarbonized by the hot exhaust gas from the rotary kiln, and are separated from the gas in the lowest cyclone and supplied to the rotary kiln.

Since the combustion efficiency of combustion is not high even if a high temperature flame is generated in the center of the turning furnace, a separate post is installed between the lowest cyclone and the rotary kiln to burn unburned fuel (British Patent No. 2,142,126). Ho).

In the form using a fluidized bed, a fluidized bed is formed under the furnace to uniformly mix raw materials and fuel, and to combust the fuel by air at room temperature supplied by a fluidization fan, and to obtain high temperature (700 to 900 ° C) oxygen from the clinker cooler. Fuel is additionally combusted by the containing gas (oxygen concentration 21%) and the raw material is decarbonized.

Another type of calcination furnace is an external circulation type that increases the residence time by recycling some of the hot solid particles (raw materials and fuel) discharged from the sinter furnace into the calcination furnace to increase the residence time. System (Japanese Patent Application Laid-Open No. 60-172,341, Korean Special Publication No. 89-861).

Unlike the prior art described so far, there is also a patent relating to a process for producing a clinker using a fluidized bed kiln without using a rotary firing furnace. In the process of producing a clinker using a fluidized bed kiln, the main idea is to grow the clinker crystal in the fluidized bed kiln by recycling the fine powder clinker serving as a nucleus of the clinker reaction. In a cement clinker manufacturing apparatus (Korean Special Publication No. 90-1364) consisting of a suspension preheater and a jet bed granulating furnace, a fluidized bed kiln, and a fluidized bed cooler (Korean Special Publication No. 90-1364), a draft tube is installed in a jet bed granulating furnace. .

Since the jet bed is used as a granulating furnace for granulating fine powdered cement raw material for clinker reaction in a fluidized bed kiln, the internal temperature is also operated in the range of 1200 to 1350 ° C. to allow the liquid phase of the cement raw material to be formed. Therefore, the technical idea and the object of the present invention are different from the present invention which uses a draft tube and calcinates in a rotary firing furnace to improve the decarbonation rate of the raw material by adjusting the residence time of the cement raw material and the fuel, and to increase the combustion efficiency of the fuel.

In the conventional method of calcining cement clinker using a rotary kiln, it is well known that the solid fuel burned in the kiln is often combustible bituminous coal, but the combustion efficiency of the fuel is less than 90%. Therefore, unburned carbon that cannot be burned in the calciner enters the rotary kiln and is burned in the kiln furnace inlet by the high temperature (900-1100 ° C.) rotary kiln exhaust gas. Combustion of unburned carbon creates a local reducing atmosphere at the inlet of the rotary kiln, so the volatilization of alkali and sulphide in the raw materials is increased, forming a tongue, which plays a major role in instability of the process. In order to prevent unburned carbon from entering the rotary kiln, the combustion efficiency of fuel in the kiln should be high. Factors affecting the combustion hole of the fuel include oxygen concentration inside the furnace, combustion atmosphere gas temperature, fuel temperature, and residence time of the fuel in the furnace. Since the particle size, oxygen concentration, and temperature of the fuel are fixed according to the device, it is convenient to adjust the residence time of the fuel to increase the combustion effect.

In the method using the fluidized bed, the residence time of the raw material and the fuel is about 1 minute in the fluidized bed, but the temperature in the fluidized bed is about 770 ° C., so the combustion speed of the fuel is slow, and a system using a swirling furnace (US Pat. No. 3,834,860) Since the raw materials and fuel are decarbonized and combusted while turning in the furnace, the raw materials and unburned fuel are moved down to the furnace wall by centrifugal force and lowered and discharged into the mixing chamber. And residence time for decarbonation is short.

In addition, even if a hot flame is formed in the central portion of the turning calcining furnace, gas-solid heat transfer is not excellent because of poor mixing of the gas and the raw material. Since all combustion flue gas from the slewing furnace is supplied to the mixing chamber 15, the oxygen concentration for burning unburned carbon in the mixing chamber becomes scarce, and the gas flow rate in the mixing chamber is increased due to many combustion gases. There is a problem that the time is shortened. In this system, the residence time of the gas is 3-4 seconds and the residence time of the solid particles is 10-12 seconds, and it is difficult to increase or control the residence time for the complete combustion of the lower fuel and unburned carbon.

In a system for burning unburned fuel by placing a separate post between the lowest cyclone and a rotary kiln (UK Patent No. 12,142,126), a separate apparatus is required to install a fluidizing fan and a fluidizing air distribution plate. Since there is a heat energy loss, and if the operation of the equipment is not smooth, the lowest cyclone is blocked, the operation is impossible to plasticizer.

In the method using the jet-sorting layer, the gas residence time in the gas furnace is 2 to 3 seconds, and the residence time of the solid is 10 to 15 seconds. It is difficult to control the residence time of the solid particles in order to obtain, and it is difficult to treat the coarse solid having a large particle size. In order to recycle solid raw materials and fuels into plasticizers in an external circulation system, a separate in-house facility such as cyclone is required, so that the heat dissipation loss is large and a circulating fluidized bed is used (Korea Special Publication No. 1539) to distribute the fluidization gas. Since the plate is required and the pressure loss in the distribution plate is large, there is a disadvantage in that the power cost for driving is high.

Accordingly, an object of the present invention is to provide a plasticizer for cement raw materials which can eliminate the problems in the known method described above, and also decarbonize and burn coarse raw materials or fuels with large particle sizes to perform more efficient and stable operation. have.

Hereinafter, the present invention will be described in detail.

The present invention is located between a suspension preheater and a rotary firing furnace for preheating granular or powdery raw materials during the firing process for manufacturing a cement clinker, and in a plasticizer which burns a separate fuel from the rotary firing furnace and simultaneously decarbonates the raw materials ( 1) At least one means for supplying the preheated raw material separated from the gas in the fractionation bed reactor, cyclone separator, suspension type preheater to the furnace is installed. (2) The decarbonized raw material is discharged from the upper part of the furnace to the lowest stage. Means for introducing into the cyclone are provided, and (3) at least one fuel supply means is installed in the lower part of the furnace or in the annulus area to combust the fuel separately from the rotary firing furnace, and (4) (5) At least two combustion air for combustion of fuel supplied to the furnace Divided by airflow on the top, one is injected through the nozzle under the fractionation bed reactor and the other is supplied to the middle part of the furnace, and (6) the draft tube to increase or control the internal circulation of solid particles at the bottom of the furnace. Characterized in that the installation.

In addition, the present invention is located between a suspension type preheater for preheating granular or powdery raw materials and a rotary firing furnace for producing clinker minerals, wherein the plasticizer is used to decarbonize the preheated raw material in the suspension type preheater. At least one of which is provided (2) a fuel supply means for combusting fuel separately from the rotary kiln and a high temperature combustion air supply means having a high oxygen concentration from the cooler, and (3) fuel combustion flue gas and calcined fine powder. (4) One or more means for scattering and discharging particles of (4) unburned carbon and a large particle diameter are provided, and one or more means for discharging unplasticized raw materials and plasticized raw materials is installed on the side of the lower part of the furnace. (5) A mixing chamber is provided which burns unburned carbon and completes decarbonization of the raw materials. (6) The mixing chamber has a high temperature flue gas and clinker from a rotary kiln. Means for introducing high-temperature air rich in oxygen concentration from the cooler are provided. (7) A draft tube is placed in the lower part of the furnace and (8) Combustion air from the cooler supplied to the furnace and the mixing chamber. The supply duct is provided with one or more means for adjusting the flow rate to each duct, (8) characterized in that the diameter of the upper part is larger than the diameter of the lower part by dividing the plasticizer into two parts.

The fuel in the present invention may be introduced below the draft tube through the inclined portion of the upper part of the annulus region and the lower part of the furnace to the area between the outer diameter of the draft tube and the inner diameter of the furnace. The fuel supplied to the annulus region is preheated rapidly by the sensible heat of the raw material which is hot, and the volatiles are volatilized and partially combusted, and the char is moved to the lower part of the draft tube, and high temperature (700 to 900 ° C) from the cooler is used. Since combustion is carried out in the draft tube by the enriched (21%) combustion air, no hot spots are generated inside the furnace, so that no coating is produced and a uniform temperature distribution can be obtained in the furnace.

Fuel is liquid fuel, fuel oil and solid fuel are bituminous coal, which is composed of anthracite coal, lignite coal, petroleum shale, coal shale, and industrial waste.

One or more pieces of air entering the gas furnace as secondary air are mounted on the upper part of the draft tube and are discharged from the draft tube to burn unburned fuel and carbon monoxide in the rising fuel to cause complete combustion of the fuel. The residence time is increased by increasing the internal circulation by reducing scattering. The behavior of the solid raw material in the bottom of the plastic furnace shows that the solid raw material is virtually elevated by the combustion air from the cooler inside the draft tube and descends in the annulus region. The flow inside the draft tube has a low solids density and a high solids density in the annulus region. This work difference causes a solid material internal circulation between the interior of the draft tube and the annulus region.

According to the present invention, the raw material collected in the suspension type preheater is partially branched and supplied to the exhaust gas duct from the rotary kiln, thereby effectively utilizing the high temperature (900-1100 ° C.) flue gas sensible heat and reducing the amount of raw material supplied to the calcining furnace. Improve fuel combustion assistance in the furnace.

The raw material (60 to 90% of the total raw material input amount) introduced into the plastic furnace is supplied to the upper part of the annulus region and the draft tube through one or more raw material input means.

The decarbonized material in the upper portion of the draft tube is discharged by moving upward to the calciner by the rising air, and the non-decarbonized fuel is lowered to the annulus area, and the draft tube is caused by the air rising from the nozzle at the bottom of the furnace. As it rises inside, it is decarbonated by the heat of combustion of the fuel, lightens, and moves upward to the calciner and is discharged.

Since the raw material that is not decarboxylated is moved back to the annulus region and recycled, the decarboxylation rate of the raw material is very high and uniform under thermal energy. Raw material supplied to the annulus region is also decarbonized through the above path.

Hereinafter, described in more detail according to the accompanying drawings of the present invention.

1 is a view schematically showing a thermotreatment apparatus for granular or powdery cement raw material attached to a plastic furnace equipped with a draft tube for internal circulation of solid particles of cement raw material.

According to the present invention, the granular or powdery raw material such as cement is supplied to the suspension type preheater through the raw material inlet 9 in FIG. 1 and suspended by the gas rising from the cyclone C4 to the cyclone C5. It moves and descends along the cyclone (C5? C4? C3? C2), but is preheated by the exhaust gas discharged from the calcining furnace 3 and the rotary firing furnace 1, as will be described later.

A portion (about 10-40%) of the raw material collected in the cyclone (C2) is then supplied to the exhaust gas conduit (7) of the rotary kiln (1), which is the high temperature (900-900) discharged from the rotary kiln (1). It is for using the exhaust gas of 1100 degreeC) efficiently.

Meanwhile, as shown in FIG. 1, the calcining furnace 3 for decarbonization of raw materials includes an upper portion 3a, a lower portion 3b, a draft tube 6, and combustion air supply conduits 4a and 4b. In this case, the diameter of the lower portion 3b of the plasticizer 3 is larger than the upper portion 3a, and the draft tube 6 is provided on the lower portion 3b side. Therefore, the draft tube 6 causes internal circulation of the solid particles to increase the residence time.

In the gas furnace 3 according to the present invention, most of the raw material separated from the gas in the cyclone C2 (about 60 to 90%) is supplied through the duct 8, wherein the raw material is supplied to the gas furnace. The upper and lower portions of the draft tube 6 of the bottom of the furnace 3b through the raw material injection conduits 8b and 8c provided above, and the annulus region 6b between the draft tube 6 and the inner wall surface of the bottom of the furnace 3b. Is supplied. The raw material thus supplied is de-carbonated by the combustion heat of the raw material by the internal combustion by the combustion air supplied through the combustion air supply conduits 4a and 4b, and ejected to the upper portion 3a of the calcining furnace 3. Discharged.

Here, the fuel is supplied to the lower portion of the draft tube 6 through one or more burners 11 installed at the inclined portion of the lower portion 3b of the plastic furnace 3 or burner mounted in the annulus region 6b. It is combusted by combustion air rich in oxygen concentration (21%) from the cooler 2 supplied through (11) and ejected through the combustion air supply conduit 4b.

According to the present invention, the large and unburned fuel ejected from the draft tube 6 moves to the annulus region 6b and descends and is burned in contact with the combustion air again to increase the combustion efficiency of the fuel. do. Moreover, unburned fuel in the fuel ejected from the lower part 3b of the furnace 3 is further burned by the combustion air supplied through the combustion air supply conduit 4a in the upper part 3a of the furnace 3. This results in complete combustion of the fuel.

Finally, the calcined raw material discharged from the kiln 3 is separated from the exhaust gas in the cyclone C1 and supplied to the rotary kiln 1 through the duct 12 and calcined by the clinker reaction, and then in the cooler 2. Is cooled.

FIG. 2 is an enlarged view of a plasticizer for granular or powdery raw materials such as cement in FIG.

According to this figure, the diameter of the lower part 3b is larger than the diameter of the upper part 3a in the plastic furnace 3. As a result, the gas velocity in the lower portion 3b is slowed, so that the residence time of the solid particles increases, and the upper portion 3a has a smaller diameter of the lower portion 3b, so that the solid material can be smoothly discharged from the furnace. do.

In addition, a draft tube 6 is provided at the bottom of the furnace 3b to further increase the residence time of the solid particles and to control the diameter of the draft tube 6. The diameter of the draft tube 6 is a combustion air supply conduit 4b. It may be greater than or equal to the diameter of the combustion air powder tool nozzle supplied through. In addition, a damper 5 is provided in the combustion air supply conduit 4a and the combustion air supply conduit 4b to adjust the flow rates of the combustion air supplied to the lower portion 3b of the plastic furnace 3. The residence time of the solid particles supplied to the calciner 3 depends on the height of the draft tube and the ratio of the diameter of the draft tube to the calciner and is controlled by adjusting the flow rate of the combustion air. Therefore, the design of the device is easy according to the material to be treated.

2 (a) or 2 (b), an enlarged view of the lower portion 3b of the gas furnace in which the draft tube 6 is installed. According to the present invention, the draft tube 6 is provided in a plurality of supports 20. As shown in FIG. By the plasticizer it is located in the center of the lower portion (3b).

2 (b) is an internal plan view of the plasticizer lower portion 3b provided with the draft tube 6 by cutting the lower portion 3b along the AA line in FIG. 2 (b). According to this, a number of supports 20 are plasticized to support the draft tube 6 against the side of the lower portion 3b.

On the other hand, the secondary air supplied to the upper portion (3a) of the plastic furnace (3) through the combustion air supply conduit (4a) may be supplied to the plastic furnace in the perpendicular or tangential direction. By introducing the plastic furnace 3 in the tangential direction, a vortex is formed in the upper portion 3a of the plastic furnace 3, thereby increasing the residence time of the solid raw material and increasing the decarbonation rate of the raw material. In the case where the gas is supplied to the plastic furnace 3 in another direction for another purpose, the pressure loss is reduced, thereby reducing the power cost. The amount supplied to the secondary air is about 10 to 30% of the total amount of air supplied to the gas furnace within the range capable of smoothly burning the fuel and internal circulation of the solid material and the fuel at the bottom of the gas furnace 3b. It is preferable.

On the other hand, the gas velocity at the bottom of the furnace is preferably maintained at 0.5 to 6 m / sec, more preferably at 0.5 to 4 m / sec. It is preferable that the velocity of gas in the upper part of a calcination furnace shall be 4-8 m / sec. The exhaust gas duct from the rotary kiln is preferably sized to maintain a flow rate of 15 to 30 m / sec in consideration of the addition of 10 to 40% of the raw material. The solid residence time in the calcining furnace can be controlled from 1 to 30 minutes depending on the amount of solid retention in the annulus region, preferably 1 to 8 minutes.

3 is a view schematically showing another embodiment of a granular or powdery raw material thermal treatment apparatus such as cement according to the present invention.

According to the present invention, the powdery or granular cement material introduced into the raw material inlet 9 is sequentially heated in a cyclone (C5-> C4-> C3-> C2) by exhaust gas from the rotary firing furnace 1 and the calcining furnace 3. Then, it is supplied to the plasticizer 3 through the raw material input conduit 8 and then decarbonated and supplied to the mixing chamber 15 through the discharge conduit 16. The raw material and unburned carbon supplied to the mixing chamber 15 are further decarbonized and combusted by the high temperature (900 to 1100 ° C) exhaust gas from the rotary firing furnace 1 to burn the exhaust conduit 14 in the calcining furnace 3. Along with the raw material of the fine powder discharged through the cyclone (C1) is separated from the gas is supplied to the rotary baking furnace (1) through the duct (12).

4 is a diagram schematically showing an enlarged portion of the plasticizer 3 in the middle of the third way.

In the present invention, a granular or powdery raw material calcining apparatus such as cement is composed of a calcining furnace (3), a mixing chamber (15), and a draft tube (6) for promoting internal circulation of a solid raw material. Is divided into the upper part 3a and the lower part 3b, and the draft tube 6 is installed in the lower part 3b of the furnace 3 to promote internal circulation of raw materials and fuels, and The diameter is larger than that of the lower portion 3b, thereby reducing the amount of fine powder and fuel scattered from the plasticizer 3, and increasing the residence time of solid particles in the lower portion of the plasticizer 3b to decarburize the fuel. The combustion efficiency of the product and fuel is increased.

On the other hand, the raw material collected from the cyclone (C2) is passed through the raw material input conduit (8) through at least one conduit (8a, 8b) to the plasticizer furnace 3b of the annulus region (6b) and the draft tube upper Each is supplied.

The supplied raw material descends the annulus region 6b and moves from the lower portion of the draft tube 6 to the inside of the draft tube 6 6a by the combustion air, and is decarbonized by the heat of combustion of the fuel. The decarbonated light particles and fine powder are discharged through the discharge conduit 14 and supplied to the upper portion of the mixing chamber 15. The raw material having a larger particle size and requiring more decarbonation moves to the annulus region 6b and descends.

The fuel supplied to the gas furnace 3 is supplied through the burner 11 provided in the inclined part of the bottom of the furnace, or through the burner 11 provided in the annulus area 6b, and from the cooler 2 It is mainly burned in the draft tube 6a by the oxygen-containing gas of high temperature (700-900 degreeC). Combustion air supplied from the cooler (2) through the combustion air supply conduit (4) is branched into the conduit (17) and the conduit (18), and controls the internal circulation of the solid raw material in the furnace 3, fuel The amount of combustion air supplied through the conduit 17 for the combustion of is controlled by the damper 5. The remaining combustion air is supplied to the mixing chamber 15 through the conduit 18 so that the unburned carbon discharged through the exhaust conduit 16 in the calciner 3 is high (900 to 1100) from the rotary calciner 1. The combustion efficiency of the fuel is improved by providing a high concentration (21%) of oxygen when combusted while being mixed with the exhaust gas of ℃) to improve the combustion conditions.

The combustion flue gas in the gas furnace 3 is discharged from the upper part of the gas furnace through the discharge conduit 14 and supplied to the upper part of the mixing chamber 15, so that combustion conditions of the unburned fuel in the lower part of the mixing chamber are improved.

The exhaust gas from the rotary firing furnace 1 is injected at a high speed (20-40 m / sec) through the nozzle 13 to prevent the raw material discharged from the calcining furnace 3 from falling into the rotary firing furnace 1. The fuel supplied from the burner 19 installed in the nozzle 13 reduces the air pollution by reducing the nitrogen oxide generated in the rotary firing furnace 1.

The combustion air supplied to the mixing chamber 15 is preferably 10 to 20% of the combustion air supplied through the combustion supply conduit 4. The internal temperature in the plastic furnace 3 can be maintained at a wide temperature method of 840 to 1150 占 폚, but preferably at 860 to 900 占 폚. In the present invention, the velocity of the combustion air supplied through the conduit 17 is 0.5 to 3 m / sec and is kept smaller than the flow rate of the combustion air supplied through the conduit 4b in FIG. Most of the raw material discharged through the discharge conduit 16 is introduced into the lowest cyclone (C1) via the mixing chamber 15, so the gas velocity in the mixing chamber is preferably maintained at 4-20 m / sec, but 8-15 m / sec. It is preferable to keep it as. Solid fuel burned in the present invention can burn a fuel having an average particle diameter of 20 to 500μm, but a fuel of 100 to 350μm is preferable.

The draft tube 6 is installed in the lower part 3b of the gas furnace 3 to promote internal circulation of raw materials and fuels, and the diameter of the upper part 3a is larger than the lower part 3b, so that the gas furnace 3 In this case, the amount of fine powders and fuels that are scattered out of the fuel is reduced, and the residence time of the solid particles is increased in the lower part of the calcining furnace 3b, thereby increasing the decarbonization rate of the raw materials and the combustion efficiency of the fuel.

On the other hand, the raw material collected from the cyclone (C2) is passed through the raw material input conduit (8) through at least one conduit (8a, 8b) to the plasticizer furnace 3b of the annulus region (6b) and the draft tube upper Each is supplied.

The supplied raw material descends the annulus region 6b and moves from the lower part of the draft tube 6 to the inside of the draft tube 6 6a by the combustion air, and is decarbonized by the heat of combustion of the fuel. The decarbonated light particles and fine powder are discharged through the discharge conduit l4 and supplied to the upper portion of the mixing chamber 15. The raw material having a larger particle size and requiring more decarbonation moves to the annulus region 6b and descends.

The fuel supplied to the gas furnace 3 is supplied through the burner 11 provided in the inclined part of the bottom of the furnace, or through the burner 11 'provided in the annulus area 6b, and from the cooler 2 It is mainly burned in the draft tube interior 6a by the high temperature (700-900 degreeC) oxygen containing gas. Combustion air supplied from the cooler (2) through the combustion air supply conduit (4) can also burn low-grade fuel having a slow speed in the conduit (17) and the conduit (18). By reducing the amount of unburned carbon that enters to stabilize the volatilization behavior of volatiles such as alkali, sulfur compounds to stabilize the operation of the firing process. In addition, since the size of the plastic furnace is smaller, the solid throughput per unit volume is increased, the initial equipment investment cost is reduced, and the heat dissipation loss is reduced to save energy.

The draft tube provides excellent heat transfer between the internally circulating solid particles and the combustion air, and does not form a coating at the fuel injection position due to the behavior of the internally circulating solid particles even when operating in a high temperature range (900 to 1100 ° C). Therefore, stable operation can be performed, complete combustion of fuel can be obtained, and complete decarbonation of raw materials can be obtained.

In addition, since the solid residence time in the furnace can be increased and controlled, the decarburization rate of the raw material is increased and made uniform, and the heat load in the rotary kiln is reduced, which extends the life of refractory softening. It leads to drug and production increase.

Increasing and controlling the residence time makes it possible to burn low-grade fuels with slow burning speeds, and to burn power and coarse fuels and raw materials, and to decarbonize them. The residence time of the solid particles can be controlled by adjusting the outside diameter ratio of the draft tube and the plasticizer, the actual height of the draft tube, and the flow rate of the combustion gas supplied to the nozzle during operation, so that the device can be easily designed for various raw materials and fuels. Do.

Claims (11)

It is located between the suspension type preheater for preheating granular or powdery raw materials such as cement and the rotary firing furnace which calcinates decarbonated raw materials to make clinker minerals, and introduces high-temperature combustion air from the cooler to burn fuel separately from the rotary firing furnace. In the calcining apparatus which decarbonizes the preheated raw material from the suspension type preheater by the combustion heat, a means for discharging the calcined raw material to the lowest cyclone C1 is provided, and is connected to the bottom of the calcining furnace 3b. A combustion furnace duct connected to the combustion air duct from the cooler as secondary combustion air, and a combustion furnace upper portion 3a which completely burns the unburned carbon of fine powder ejected from the lower portion of the furnace and completes decarbonization of the raw material; The plasticizer is connected to the upper portion (3a) and connected to the bottom means for introducing the combustion air from the cooler, and one or more means for introducing the preheated raw material from the suspension preheater is installed, The gas furnace 3b is provided with at least one means for separately supplying fuel so as to decarbonize the raw material simultaneously with combustion of the fuel; The plasticizer of the cement raw material using the internal circulation, characterized in that the draft tube (6) is installed to increase and adjust the residence time of the solid raw material and fuel in the bottom of the furnace 3 (b). 2. The plasticizer for cement raw material using internal circulation according to claim 1, wherein the lower part of the furnace 3b has a diameter larger than that of the upper furnace 3a in order to increase the residence time of the solid material in the lower part. . 2. The gas furnace 3, lower part 3b, is connected to a means 4b for supplying at least a portion of the fuel combustion air separated from the cooler 4 by at least two, and the gas furnace 3 Side), means (4a) for supplying at least a portion of the remaining fuel combustion air to the secondary combustion air is connected, the plasticizer of the cement raw material using the internal circulation. 4. The combustion air supply means connected to the bottom of the furnace 3b and the secondary combustion air supply means connected to the side of the furnace have a volume ratio of 1: 1. The plasticizer of the cement raw material using the internal circulation, characterized in that it is adjusted to be supplied to the range from 1: 9. The combustion air supply means connected to the lower part 3b of the furnace 3 has a flow rate of the combustion air in the draft tube of the lower part of the furnace 3b. A plasticizer for cement raw material using internal circulation, characterized in that the size is set so that it can pass at a speed of sec. 4. The combustion air supply means connected to the side of the furnace 3 is installed so that combustion air can be supplied to the side of the furnace 3 in a tangential or perpendicular direction. Plasticizer of Cement Raw Material Using Internal Circulation The plasticity of cement raw material using internal circulation according to claim 1, characterized in that the diameter of the draft tube (6) is greater than or equal to the diameter of the combustion air supply means connected to the lower portion (3b). Device. 4. The plasticizer for cement raw material using internal circulation according to claim 2 or 3, wherein the combustion air supply means is provided with at least one means (5) for adjusting the amount of combustion air. Located between a suspension hung preheater for preheating granular or powdery raw materials such as cement and a rotary firing furnace that calcinates decarbonated raw materials to produce clinker minerals, while burning fuel with hot combustion air introduced from the cooler separately from the rotary firing furnace. In the plasticizer which decarbonizes the preheated raw material from a suspension type preheater by this combustion heat, At least one raw material supply means from a suspension preheater is provided and the combustion air supply for combusting the fuel supplied separately from a rotary kiln is provided. At least one means is installed, at least one means for discharging the decarbonized raw material is installed, and a lower portion of the furnace is provided with a draft tube (b) for increasing or controlling the residence time through internal circulation of the solid material. 3b); In order to reduce the amount of raw materials and unburned carbon bleed out from the bottom of the furnace 3b, the diameter of the furnace is larger than that of the bottom 3b, and means for discharging the combustion exhaust gas are installed, and the top of the furnace 3a; Mixing chamber for further decarbonation and combustion of raw materials and small amounts of unburned carbon discharged from the calcining furnace lower part 3b by hot air from the rotary firing furnace 1 to proceed with complete combustion of the decarbonization of the raw materials and fuel (15). Plasticizer of cement raw material using the internal circulation, characterized in that consisting of. 10. The combustion air supply means (4) according to claim 9, wherein the combustion air supply means (4) separates the combustion air from the cooler required in the furnace (1) into at least two streams to calcinate most of the combustion air to primary combustion air. A means (17) for combusting fuel by supplying it to the lower part of the furnace (3b) and fluidizing the supplied raw material and fuel, and supplying the remaining air to the mixing chamber (15) as secondary air and discharging it from the gas furnace (3). Apparatus for calcining cement raw materials using internal circulation, characterized in that branched to means (8) for promoting combustion of unburned carbon. 11. The combustion air supply means (17, 18) according to claim 9 or 10, means for adjusting the amount of primary air and secondary air (10: 1 to 7: 1: 1) by volume ratio A calcining apparatus for cement raw material using internal circulation, which specifies that it is installed.