CA1079065A - Cement calcining apparatus - Google Patents
Cement calcining apparatusInfo
- Publication number
- CA1079065A CA1079065A CA268,388A CA268388A CA1079065A CA 1079065 A CA1079065 A CA 1079065A CA 268388 A CA268388 A CA 268388A CA 1079065 A CA1079065 A CA 1079065A
- Authority
- CA
- Canada
- Prior art keywords
- burner
- fuel
- furnace
- constant
- suspension
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- 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
- F27B7/2016—Arrangements of preheating devices for the charge
- F27B7/2025—Arrangements of preheating devices for the charge consisting of a single string of cyclones
- F27B7/2033—Arrangements of preheating devices for the charge consisting of a single string of cyclones with means for precalcining the raw material
-
- 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
- C04B7/434—Preheating with addition of fuel, e.g. calcining
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Ceramic Engineering (AREA)
- Structural Engineering (AREA)
- Thermal Sciences (AREA)
- Materials Engineering (AREA)
- Physics & Mathematics (AREA)
- Organic Chemistry (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Curing Cements, Concrete, And Artificial Stone (AREA)
- Furnace Details (AREA)
- Feeding, Discharge, Calcimining, Fusing, And Gas-Generation Devices (AREA)
- Crucibles And Fluidized-Bed Furnaces (AREA)
- Muffle Furnaces And Rotary Kilns (AREA)
Abstract
CEMENT CALCINING APPARATUS
ABSTRACT OF THE DISCLOSURE
A cement calcining apparatus having a suspension preheater with a precalcining furnace, said precalcining furnace is provided with a constant-feed burner to which a rated amount of pulverized coal of specified density or the like solid fuel having the same property as of the coal is always being blasted and a load control burner for control-ling the amount of the pulverized coal or the like solid fuel having the same property as of the coal to be blasted in response to the variation of load.
Whereby said calcining apparatus is enabled to have a wide range of load control.
ABSTRACT OF THE DISCLOSURE
A cement calcining apparatus having a suspension preheater with a precalcining furnace, said precalcining furnace is provided with a constant-feed burner to which a rated amount of pulverized coal of specified density or the like solid fuel having the same property as of the coal is always being blasted and a load control burner for control-ling the amount of the pulverized coal or the like solid fuel having the same property as of the coal to be blasted in response to the variation of load.
Whereby said calcining apparatus is enabled to have a wide range of load control.
Description
1079~65 This invention relates to cement calcining apparatus.
Calcining furnaces are known in which the material to be calcined is carried in suspension in hot combustion gas to be efficiently preheated by heat exchange with the gas so that the material granules are well dried and heated. In the cement industry, cement calcining apparatus with a suspension preheater has been generally utilized in which material is carried in suspension in hot gases drawn from the kiln exhaust for such preheating.
Lately cement calcining apparatus has come to be put in practice in which a calcining device is provided in the preheater section to simultaneously effect combustion of fuel and calcining of the material with the use of heavy oil as fuel.
Calcining in such a device has the advantages that the material and fuel are in a mixed state and combustion and heat conduction are performed in the shortest possible time, and the material is effectively precalcined for most effective subsequent processing, e.g. in cement production the material reaches the kiln entrance at a line standard of 85 - 90%.
It is known that the combustion of pulverized coal is such that firstly volatile fractions are released and burnt and then -the carbon is burnt. In the past, the speed of blowing a suspension of pulverized coal into a furnace was generally at -least 25 - 35 m/s for avoiding blow-back of flame, however, (1) when pulverized coal suspension is blown with this speed into a caicining furnace, combustion may be incomplete because of insufficient generation of volatile fractions in the furnace;
Calcining furnaces are known in which the material to be calcined is carried in suspension in hot combustion gas to be efficiently preheated by heat exchange with the gas so that the material granules are well dried and heated. In the cement industry, cement calcining apparatus with a suspension preheater has been generally utilized in which material is carried in suspension in hot gases drawn from the kiln exhaust for such preheating.
Lately cement calcining apparatus has come to be put in practice in which a calcining device is provided in the preheater section to simultaneously effect combustion of fuel and calcining of the material with the use of heavy oil as fuel.
Calcining in such a device has the advantages that the material and fuel are in a mixed state and combustion and heat conduction are performed in the shortest possible time, and the material is effectively precalcined for most effective subsequent processing, e.g. in cement production the material reaches the kiln entrance at a line standard of 85 - 90%.
It is known that the combustion of pulverized coal is such that firstly volatile fractions are released and burnt and then -the carbon is burnt. In the past, the speed of blowing a suspension of pulverized coal into a furnace was generally at -least 25 - 35 m/s for avoiding blow-back of flame, however, (1) when pulverized coal suspension is blown with this speed into a caicining furnace, combustion may be incomplete because of insufficient generation of volatile fractions in the furnace;
(2) part of the pulverized coal may be driven in a state of incomplete combustion from the furnace into the material supply cyclones and there tends to make secondary combustion, this causes clogging of cyclones;
(3) as incompletely burnt pulverized coal may enter mixed with the material into the kiln, temperature distribution in the .~ .
-~ -2-~ ' .
', ' ',:. - . ' - . , '~ . . ' - , , ' . :, ~079065 kiln varies, tending to produce caking.
For these reasons pulverized coal has not hitherto been conveniently used as fuel for calcining cement material in this type of device. Further, combustion control using pulverized coal is more difficult as compared with fluid fuels (heavy oil or gas), because of the following.
(1) The combustion of the carbon in pulverized coal takes longer than with heavy oil or gas, thus it is necessary to provide more effective combustion in the calcining device.
(2) When starting up or with the plant under little or no load, it is necessary to lessen the amount of pulverized coal, however, for the sake of security, flow in the coal blast tube has to be maintained at 25 - 35 m/s. As a result, the density of pulverized coal becomes thin and combustion in the calcining device becomes very low. For this reason, for the combustion of pulverized coal in the furnace of such system it has been proposed to provide a plurality of burner units, changes in load or output being met by some one or more of the burner units being turned on or off individually for control, while if using heavy oil or gas load control is more simple as it can be carried out not only by varying the amount of fuel blown in suspension.
The object of the present invention is to provide a calcining device in which pulverized fuels can be used while providing for a wide range of load control, enabling efficient combustion in a stable manner while avoiding clogging of cyclones due to secondary combustion, so as to obtain effectively calcined material ready for subsequent processing.
According to the invention there is provided calcining apparatus including a furnace into which material to be calcined is fed, a source for operatively providing a flow of pulverized fuel in suspension, a constant-feed burner in said furnace, constant-feed mechanism supplied with fuel from said flow in use and operable to feed it in suspension at a predetermined constant ':
.
rate to said burner, and a load-control burner in said furnace having connection to said source independently of the constant-feed mechanism, the supply of fuel to the latter burner being selectively adjustable to control the total amount of pulverized fuel supplied to the furnace to meet variations in load.
Other features and objects of the invention will be better understood from the detailed description of a typical embodiment illustrated in the accompanying drawings, in which:
Figure 1 is a diagrammatic front view of a cement plant using pulverized coal as fuel, Figure 2 is a longitudinal sectional view of a cement calcining furnace of said plant, and Figure 3 is a graph of gas analysis related to the speed of flow of pulverized coal in suspension in the calcining -furnace.
In Figure 2, numeral 4 generally designates a calcining --furnace. 13, 14 are hot air entrances from a heat exchanger.
15 are raw material chutes for feeding in material to be calcined.
22 is a coal feed tube leading directly to a load control burner 24. 26 is a coal hopper with a constant rate mechanical feeder 27 for feeding coal by way of a coal blast tube 30 to a constant-feed burner 32. 23, 31 are flexible hoses for permitting adjustment of the burner nozzle positions to avoid damage of the furnace wall caused by contact of coal flame thereto or to avoid depositing of ash thereon.
In the cement apparatus including said calcining furnace 4 shown in Figure 1, material supplied from a feeder 10 passes through cyclone 9, cyclone 8 and cyclone 7 successively, is 30 preheated by heat exchange with hot gas, and then enters the - -furnace 4. For combustion, hot air is supplied through entrances 13, 14 from a heat exchanger 3 at the exhaust from rotary kiln 2. A fuel source comprises a feeder 16 from which
-~ -2-~ ' .
', ' ',:. - . ' - . , '~ . . ' - , , ' . :, ~079065 kiln varies, tending to produce caking.
For these reasons pulverized coal has not hitherto been conveniently used as fuel for calcining cement material in this type of device. Further, combustion control using pulverized coal is more difficult as compared with fluid fuels (heavy oil or gas), because of the following.
(1) The combustion of the carbon in pulverized coal takes longer than with heavy oil or gas, thus it is necessary to provide more effective combustion in the calcining device.
(2) When starting up or with the plant under little or no load, it is necessary to lessen the amount of pulverized coal, however, for the sake of security, flow in the coal blast tube has to be maintained at 25 - 35 m/s. As a result, the density of pulverized coal becomes thin and combustion in the calcining device becomes very low. For this reason, for the combustion of pulverized coal in the furnace of such system it has been proposed to provide a plurality of burner units, changes in load or output being met by some one or more of the burner units being turned on or off individually for control, while if using heavy oil or gas load control is more simple as it can be carried out not only by varying the amount of fuel blown in suspension.
The object of the present invention is to provide a calcining device in which pulverized fuels can be used while providing for a wide range of load control, enabling efficient combustion in a stable manner while avoiding clogging of cyclones due to secondary combustion, so as to obtain effectively calcined material ready for subsequent processing.
According to the invention there is provided calcining apparatus including a furnace into which material to be calcined is fed, a source for operatively providing a flow of pulverized fuel in suspension, a constant-feed burner in said furnace, constant-feed mechanism supplied with fuel from said flow in use and operable to feed it in suspension at a predetermined constant ':
.
rate to said burner, and a load-control burner in said furnace having connection to said source independently of the constant-feed mechanism, the supply of fuel to the latter burner being selectively adjustable to control the total amount of pulverized fuel supplied to the furnace to meet variations in load.
Other features and objects of the invention will be better understood from the detailed description of a typical embodiment illustrated in the accompanying drawings, in which:
Figure 1 is a diagrammatic front view of a cement plant using pulverized coal as fuel, Figure 2 is a longitudinal sectional view of a cement calcining furnace of said plant, and Figure 3 is a graph of gas analysis related to the speed of flow of pulverized coal in suspension in the calcining -furnace.
In Figure 2, numeral 4 generally designates a calcining --furnace. 13, 14 are hot air entrances from a heat exchanger.
15 are raw material chutes for feeding in material to be calcined.
22 is a coal feed tube leading directly to a load control burner 24. 26 is a coal hopper with a constant rate mechanical feeder 27 for feeding coal by way of a coal blast tube 30 to a constant-feed burner 32. 23, 31 are flexible hoses for permitting adjustment of the burner nozzle positions to avoid damage of the furnace wall caused by contact of coal flame thereto or to avoid depositing of ash thereon.
In the cement apparatus including said calcining furnace 4 shown in Figure 1, material supplied from a feeder 10 passes through cyclone 9, cyclone 8 and cyclone 7 successively, is 30 preheated by heat exchange with hot gas, and then enters the - -furnace 4. For combustion, hot air is supplied through entrances 13, 14 from a heat exchanger 3 at the exhaust from rotary kiln 2. A fuel source comprises a feeder 16 from which
-4-~.079065 coal is fed to be pulverized in a coal crusher 17 and led via a bucket elevator 18 to enter a grading separator 19 in granulated form. Air is supplied by a fan 20 to convey the pulverized fuel flow in suspension by way of a flow separator 21 where it is divided into two streams, one for load control burner 24 and the other for constant-feed burner 32. The former stream passes directly through coal feed tube 22 to be blown in suspension into the furnace 4 by the load control burner 24. The latter stream is collected in a cyclone 25 and stored in a hopper 26.
Coal is drawn from hopper 26 by the constant rate feeder 27 and is conveyed with a fan 28 utilizing exhaust gas from cyclone 25 to enter in suspension through the constant-feed burner 32 into the furnace 4. The material calcined in the furnace 4 is advanced to a mixing chamber 5 wherein the material is mixed with exhaust gas from main kiln 2. The material thus further calcined is passed to cyclone 6. Then the material is supplied to the main rotary kiln 2.
When cement material is calcined with pulverized coal fuel in suspension from the constant-feed burner even at a minimum rate of about 20% of the coal fuel supplied by both burners at their maximum load, it is found that a good result can be obtained, thus adjustment to suit the load of the plant can be widely changed by regulating only the fuel supplied to the load control burner. Division of the coal for constant-feed blasting from that for load control is controlled by selective adjustment of the flow separator 21 independently of the constant-feed mechanism associated with burner 32, the suspension of fuel for the latter being provided separately from the suspension formed at the fuel source by fan 20.
The coal blasting tubes 24, 32 of the burner adjacent to the furnace may be made wide to slow the speed of flow of the suspension and to allow time for the generation of volatile fractions in the calcining furnace to promote the full combustion of the coal in the calcining furnace. This is illustrated in Figure 3. By slowing the speed of the coal fuel suspension (shown on the graph as "blasting speed") to 8 - 10 m/s, it shows in gas analysis 8 - 12% increase in carbon dioxide (C02) in the furnace. By providing the supply of fuel to burner 32 at a predetermined rate above the minimum needed for stability of combustion in furnace 4 and independently from that supplied to the load control burner 24 which can be adjusted to meet variations in load, stable combustion may be maintained even at times of low load when burner 24 may be shut down completely.
In the above description reference is made only to pulverized coal. However, it is to be understood that other solid fuels having the same properties as pulverized coal, for example, F.O.C. (fluid oil cokes) by-produced as sludge in refining heavy oil may also be used.
Coal is drawn from hopper 26 by the constant rate feeder 27 and is conveyed with a fan 28 utilizing exhaust gas from cyclone 25 to enter in suspension through the constant-feed burner 32 into the furnace 4. The material calcined in the furnace 4 is advanced to a mixing chamber 5 wherein the material is mixed with exhaust gas from main kiln 2. The material thus further calcined is passed to cyclone 6. Then the material is supplied to the main rotary kiln 2.
When cement material is calcined with pulverized coal fuel in suspension from the constant-feed burner even at a minimum rate of about 20% of the coal fuel supplied by both burners at their maximum load, it is found that a good result can be obtained, thus adjustment to suit the load of the plant can be widely changed by regulating only the fuel supplied to the load control burner. Division of the coal for constant-feed blasting from that for load control is controlled by selective adjustment of the flow separator 21 independently of the constant-feed mechanism associated with burner 32, the suspension of fuel for the latter being provided separately from the suspension formed at the fuel source by fan 20.
The coal blasting tubes 24, 32 of the burner adjacent to the furnace may be made wide to slow the speed of flow of the suspension and to allow time for the generation of volatile fractions in the calcining furnace to promote the full combustion of the coal in the calcining furnace. This is illustrated in Figure 3. By slowing the speed of the coal fuel suspension (shown on the graph as "blasting speed") to 8 - 10 m/s, it shows in gas analysis 8 - 12% increase in carbon dioxide (C02) in the furnace. By providing the supply of fuel to burner 32 at a predetermined rate above the minimum needed for stability of combustion in furnace 4 and independently from that supplied to the load control burner 24 which can be adjusted to meet variations in load, stable combustion may be maintained even at times of low load when burner 24 may be shut down completely.
In the above description reference is made only to pulverized coal. However, it is to be understood that other solid fuels having the same properties as pulverized coal, for example, F.O.C. (fluid oil cokes) by-produced as sludge in refining heavy oil may also be used.
Claims (6)
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. Calcining apparatus including a furnace into which material to be calcined is fed, a source for operatively providing a flow of pulverized fuel in suspension, a constant-feed burner in said furnace, constant-feed mechanism supplied with fuel from said flow in use and operable to feed it in suspension at a predetermined constant rate to said burner, and a load-control burner in said furnace having connection to said source independently of the constant-feed mechanism, the supply of fuel to the latter burner being selectively adjustable to control the total amount of pulverized fuel supplied to the furnace to meet variations in load.
2. Apparatus as in claim 1 including a separator in said flow in which the fuel supply to the constant-feed mechanism is operatively separated from the supply to the load-control burner.
3. Apparatus as in claim 2 wherein adjustment of the fuel supply to the load control burner is effected by controlling the division of said flow by the separator.
4. Apparatus as in claim 1, 2 or 3 wherein the constant-feed mechanism comprises a cyclone, storage hopper and constant rate mechanical feeder, together with a fan for forming a suspension of the fuel independently of the suspension provided by said source in use.
5. Apparatus as in claim 1, 2 or 3 in which said burner is adapted to use pulverized coal as said fuel.
6. Apparatus as in claim 1, 2 or 3 in which said burner is adapted to use fluid oil cokes as said fuel.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2469476A JPS52108423A (en) | 1976-03-09 | 1976-03-09 | Apparatus for baking cement by using minute powdery coal |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1079065A true CA1079065A (en) | 1980-06-10 |
Family
ID=12145265
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA268,388A Expired CA1079065A (en) | 1976-03-09 | 1976-12-21 | Cement calcining apparatus |
Country Status (5)
| Country | Link |
|---|---|
| JP (1) | JPS52108423A (en) |
| AU (1) | AU507643B2 (en) |
| BR (1) | BR7608727A (en) |
| CA (1) | CA1079065A (en) |
| GB (1) | GB1563918A (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4263856A (en) * | 1979-02-08 | 1981-04-28 | Combustion Engineering, Inc. | Providing supplemental pulverized coal for load regain |
| DE3736905A1 (en) * | 1987-10-30 | 1989-05-11 | Krupp Polysius Ag | METHOD AND DEVICE FOR THE HEAT TREATMENT OF FINE GRAIN GOODS |
| JPH02134240U (en) * | 1989-04-17 | 1990-11-07 | ||
| DE4123306C2 (en) * | 1991-07-13 | 2000-05-25 | Deutz Ag | Plant for the thermal treatment of flour-like raw materials |
| JP2018118861A (en) * | 2017-01-23 | 2018-08-02 | 三菱マテリアル株式会社 | Method for producing cement |
| CN111960698A (en) * | 2019-08-20 | 2020-11-20 | 中国科学院工程热物理研究所 | Fuel supply system and method for industrial kiln equipment and industrial kiln equipment |
-
1976
- 1976-03-09 JP JP2469476A patent/JPS52108423A/en active Granted
- 1976-12-06 GB GB5113376A patent/GB1563918A/en not_active Expired
- 1976-12-21 CA CA268,388A patent/CA1079065A/en not_active Expired
- 1976-12-24 AU AU20921/76A patent/AU507643B2/en not_active Expired
- 1976-12-28 BR BR7608727A patent/BR7608727A/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| BR7608727A (en) | 1977-10-25 |
| JPS52108423A (en) | 1977-09-10 |
| AU507643B2 (en) | 1980-02-21 |
| JPS5522429B2 (en) | 1980-06-17 |
| AU2092176A (en) | 1978-06-29 |
| GB1563918A (en) | 1980-04-02 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| EP0582394B1 (en) | Method of incinerating waste in a cement kiln plant | |
| US5816795A (en) | Apparatus and method for providing supplemental fuel to a preheater/precalciner kiln | |
| US4238237A (en) | Manufacture of cement by intergrinding carbonaceous fuel | |
| US7488172B2 (en) | Methods of mixing high temperature gases in mineral processing kilns | |
| GB1428828A (en) | Apparatus for example for burning the powdered materials for making cement | |
| US6672865B2 (en) | Method of mixing high temperature gases in mineral processing kilns | |
| US4249892A (en) | Method and apparatus for the thermal treatment of pulverulent material particularly for the calcining of cement | |
| US20200392041A1 (en) | Clinker production plant and method for producing clinker in such a plant | |
| US4071309A (en) | Method and apparatus for making cement with preheater, kiln and heat exchanger for heating combustion air | |
| US4530661A (en) | Apparatus for the calcination of fine grained material | |
| US5454714A (en) | Equipment for and method of precalcining any mineral materials whatsoever | |
| CA1079065A (en) | Cement calcining apparatus | |
| US4477251A (en) | Process and apparatus for calcining pulverulent material | |
| US3519254A (en) | Method and apparatus for the control of burner heat distribution | |
| US4366000A (en) | Method and apparatus for preheating dry raw meal prior to introduction of the meal into a suspension cyclone preheater system supplying a rotary kiln | |
| GB723455A (en) | Improvements in preparation of a charge for a calcium carbide furnace | |
| US4089697A (en) | Manufacture of Portland cement | |
| JPS5920624B2 (en) | Method and apparatus for producing cement | |
| US4146360A (en) | Device for controlling the gas temperature in the drying chamber of a moving grate preheater for cement clinker production | |
| US4511333A (en) | Device for burning cement | |
| US4105460A (en) | Process for the endothermic calcination of raw material | |
| US4583943A (en) | Process for calcining pulverulent material | |
| US928512A (en) | Process of and apparatus for burning cement and like materials. | |
| SU737753A1 (en) | Unit for thermal treatment of finely disintegrated material | |
| US1949560A (en) | Burner |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |