WO2012042418A1 - A method for manufacturing cement clinker - Google Patents
A method for manufacturing cement clinker Download PDFInfo
- Publication number
- WO2012042418A1 WO2012042418A1 PCT/IB2011/054004 IB2011054004W WO2012042418A1 WO 2012042418 A1 WO2012042418 A1 WO 2012042418A1 IB 2011054004 W IB2011054004 W IB 2011054004W WO 2012042418 A1 WO2012042418 A1 WO 2012042418A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- preheater
- calciner
- exhaust gases
- kiln
- location
- Prior art date
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Classifications
-
- 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
- C04B7/364—Avoiding environmental pollution during cement-manufacturing
-
- 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
- C04B7/4407—Treatment or selection of the fuel therefor, e.g. use of hazardous waste as secondary fuel ; Use of particular energy sources, e.g. waste hot gases from other processes
- C04B7/4446—Treatment or selection of the fuel therefor, e.g. use of hazardous waste as secondary fuel ; Use of particular energy sources, e.g. waste hot gases from other processes the fuel being treated in a separate gasifying or decomposing chamber, e.g. a separate combustion chamber
Definitions
- the present invention relates to a method for manufacturing cement clinker, where cement raw materials are preheated in a preheater, calcined in a calciner being connected to a separation cyclone, burned into cement clinker in a kiln and cooled in a clinker cooler, and where second source exhaust gases are produced in second source equipment and introduced into the preheater at a location after the calciner as viewed in the direction of movement of the gases from the calciner.
- cement clinker manufacturing is associated with heavy formation of emission compounds originating from the kiln system comprising the preheater, calciner and kiln, and which compounds are unwanted in the atmosphere.
- a lot have been done during the years to limit the amount of emission compounds, which are allowed to pass into the atmosphere.
- second source exhaust gases i.e. exhaust gases originating from second source equipment being other sources than the kiln system, still need attention in order to be limited to an acceptable level.
- gases are used both for drying and transportation purposes.
- the exhaust gases from the milling department may contain gaseous species mostly in form of combustible emission compounds, being organic compounds, carbon monoxide, ammonia, etc that are harmful to the environment.
- the fuel used for firing both the calciner and the kiln may comprise fuel that originate from all kind of waste material, such as domestic waste, sludge from sewage disposal plants, furniture, tyres etc., and if prepared at site exhaust gases from the preparation may contain gaseous species also mostly in form of combustible emission compounds that are harmful to the environment.
- the fuel used for firing both the calciner and the kiln may comprise coal, which has been milled at site in a coal milling department, thus producing exhaust gases containing harmful emission compounds also mostly in form of combustible emission compounds.
- some cement plants comprise a kiln gas bypass for extracting volatile components, such as chloride, alkali and sulphur, from the kiln system.
- the exhaust gases from such bypass systems typically contain acidic emission compounds, being S0 2 /S0 3 , HCI and possibly H 2 S, and further ultra fine particles of PM2.5 and PM10, i.e. particles less than 2.5 and 10 micrometers in diameter respectively, due to condensation of alkali chlorides.
- this is achieved by a method of the kind mentioned in the introduction, and being characterized in that the temperature in the preheater at the location of introduction of the second source exhaust gases into the preheater is kept about at least 700 °C. It is hereby obtained that the environmental harmful gaseous species released from secondary sources are effectively immobilised and/or destroyed in the preheater without significant impact on the heat consumption of the kiln system and without increasing the gas flow through the kiln and calciner.
- second source exhaust gases are introduced into the preheater at a location after the separation cyclone being connected to the calciner as viewed in the direction of movement of the gases from the calciner.
- the exhaust gases originating from different second sources such as, but not limited to, cement raw material milling departments, coal milling departments, waste fuel preparation departments, kiln bypasses etc., may contain widely different emissions compounds, that need different treatment and require different operation parameter values in term of temperature, oxygen content,
- the retention time of the second source exhaust gases under such temperature conditions should preferable be at least 0.5 second, most preferably at least 1 second in order to obtain most effective burning of the combustible emission compounds contained in the second source exhaust gases.
- the second source exhaust gases should contain sufficient oxygen to ensure
- alkaline dust present in the preheater and originating from the calciner should under normal operation conditions be sufficient to effectively scrub the acidic emission compounds, being S0 2 /S0 3 , HCI and H 2 S. However, should the content of such alkaline dust for some reason be to low additional alkaline dust may be added.
- Fig. 1 shows a plant for production of cement clinker according to the invention.
- a plant for production of cement clinker comprising a cyclone preheater 1 , a calciner 3 with a separation cyclone 3a, a rotary kiln 5 and a cooler 7.
- the shown plant comprises a milling department 9 for grinding and possibly drying cement raw materials, a waste material fuel preparation department 1 1 , a coal milling department 13 and a kiln bypass 15.
- the gases are drawn through the plant via a fan 17. Further, a proportion of the exhaust gases leaving the rotary kiln is extracted from the main flow via the kiln bypass 15 and treated in per se known way in order to extract unwanted volatile components, such as chloride, alkali and sulphur from the plant.
- the second source exhaust gas emissions originating from different second sources such as, but not limited to, the cement raw material milling department 9, the waste fuel preparation department 1 1 , the coal milling departments 13 or the kiln bypass 15 in way which has minimum negative impact on the heat consumption of the kiln system and which does not increase the gas flow through the rotary kiln 5 kiln and calciner 3
- the retention time of the second source exhaust gases under such temperature conditions should preferable be at least 0.5 second, most preferably at least 1 second in order to ensure effective burning of the combustible emission compounds contained in the second source exhaust gases.
- the retention time of the second source exhaust gases may be determined by selecting a proper cross section area at the location 20 of introduction of the second source exhaust gases into the preheater 1 .
- the required oxygen to ensure burning of the combustible emission compounds in the mixed gas stream in the preheater 1 is contained in the second source exhaust gases, however should the oxygen content of the mixed gas stream in the preheater at the location 20 of introduction of the second source exhaust gases at some time during operation be below 2 % additional oxygen may be added.
- alkaline dust present in the preheater 1 and originating from the calciner 3 should under normal operation conditions be sufficient to effectively scrub the acidic emission compounds, being S0 2 /S0 3 , HCI and H 2 S. However, should the content of such alkaline dust for some reason be to low additional alkaline dust may be added.
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Structural Engineering (AREA)
- Thermal Sciences (AREA)
- Physics & Mathematics (AREA)
- Combustion & Propulsion (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Biodiversity & Conservation Biology (AREA)
- Ecology (AREA)
- Environmental & Geological Engineering (AREA)
- Environmental Sciences (AREA)
- Public Health (AREA)
- Treating Waste Gases (AREA)
- Curing Cements, Concrete, And Artificial Stone (AREA)
Abstract
A description is given of a method for manufacturing cement clinker, where cement raw materials are preheated in a preheater (1), calcined in a calciner (3) being connected to a separation cyclone (3a), burned into cement clinker in a kiln (5) and cooled in a clinker cooler (7), and where second source exhaust gases are produced in second source equipment (9, 11, 13, 15) and introduced into the preheater (1) at a location (20) after the calciner (3) as viewed in the direction of movement of the gases from the calciner (3). The method is peculiar in that the temperature in the preheater (1) at the location of introduction (20) of the second source exhaust gases into the preheater (1) is kept about at least 700 ° C. It is hereby obtained that the environmental harmful gaseous species released from secondary sources are effectively immobilised and/or destroyed in the preheater without significant impact on the heat consumption of the kiln system and without increasing the gas flow through the kiln and calciner. This is due to the fact that the relative cold exhaust gases from the secondary sources are not passed through the kiln or calciner, thus minimizing the negative impact on the heat consumption of the kiln system, while the combustible emission compounds, being organic compounds, carbon monoxide, ammonia, etc., are still effectively combusted in the preheater and the acidic emission compounds, being SO 2 /SO 3, HCl, H 2 S, are effectively scrubbed by reacting with the alkaline dust present in the preheater.
Description
A METHOD FOR MANUFACTURING CEMENT CLINKER
The present invention relates to a method for manufacturing cement clinker, where cement raw materials are preheated in a preheater, calcined in a calciner being connected to a separation cyclone, burned into cement clinker in a kiln and cooled in a clinker cooler, and where second source exhaust gases are produced in second source equipment and introduced into the preheater at a location after the calciner as viewed in the direction of movement of the gases from the calciner.
It is well known that cement clinker manufacturing is associated with heavy formation of emission compounds originating from the kiln system comprising the preheater, calciner and kiln, and which compounds are unwanted in the atmosphere. A lot have been done during the years to limit the amount of emission compounds, which are allowed to pass into the atmosphere. However, second source exhaust gases, i.e. exhaust gases originating from second source equipment being other sources than the kiln system, still need attention in order to be limited to an acceptable level. Thus, when manufacturing cement clinker cement raw materials are, prior to being introduced into the preheater, subjected to grinding and possibly drying in a milling department where gases are used both for drying and transportation purposes. The exhaust gases from the milling department may contain gaseous species mostly in form of combustible emission compounds, being organic compounds, carbon monoxide, ammonia, etc that are harmful to the environment. Further, the fuel used for firing both the calciner and the kiln may comprise fuel that originate from all kind of waste material, such as domestic waste, sludge from sewage disposal plants, furniture, tyres etc., and if prepared at site exhaust gases from the preparation may contain gaseous species also mostly in form of combustible emission compounds that are harmful to the environment. Also, the fuel used for firing both the calciner and the kiln may comprise coal, which has been milled at site in a coal milling department, thus producing exhaust gases containing harmful emission compounds also mostly in form of combustible emission compounds. In addition, some cement plants comprise a kiln gas bypass for extracting volatile components, such as
chloride, alkali and sulphur, from the kiln system. The exhaust gases from such bypass systems typically contain acidic emission compounds, being S02/S03, HCI and possibly H2S, and further ultra fine particles of PM2.5 and PM10, i.e. particles less than 2.5 and 10 micrometers in diameter respectively, due to condensation of alkali chlorides.
Attempts have been done to control such second source exhaust gas emissions by returning the gases back to the kiln system e.g. into the clinker cooler, kiln or calciner. However, the disadvantages by doing so are that it has negative impact on the heat consumption of the kiln system and increases the gas flow through the kiln and calciner. It is further known to reintroduce e.g. bypass gases into the preheater, however at too low temperatures to obtain effective burning of the combustible emission compounds contained in the second source exhaust gases.
It is the objective of the present invention to provide a method for manufacturing cement clinker, whereby the mentioned disadvantages are eliminated or at least significantly reduced. According to the present invention this is achieved by a method of the kind mentioned in the introduction, and being characterized in that the temperature in the preheater at the location of introduction of the second source exhaust gases into the preheater is kept about at least 700 °C. It is hereby obtained that the environmental harmful gaseous species released from secondary sources are effectively immobilised and/or destroyed in the preheater without significant impact on the heat consumption of the kiln system and without increasing the gas flow through the kiln and calciner. This is due to the fact that the relative cold exhaust gases from the secondary sources are not passed through the kiln or calciner, thus minimizing the negative impact on the heat consumption of the kiln system, while the combustible emission compounds, being organic compounds, carbon monoxide, ammonia, etc., are still effectively combusted in the preheater and the acidic emission compounds, being S02/S03,
HCI, H2S, are effectively scrubbed by reacting with the alkaline dust present in the preheater, whereas the ultra fine particles are led back to the kiln system.
In order to reduce the influence to a minimum on the temperature and degree of 5 calcination of the calcined cement raw meal, which is fed to the kiln from the calciner, it is preferred that second source exhaust gases are introduced into the preheater at a location after the separation cyclone being connected to the calciner as viewed in the direction of movement of the gases from the calciner. i o The exhaust gases originating from different second sources, such as, but not limited to, cement raw material milling departments, coal milling departments, waste fuel preparation departments, kiln bypasses etc., may contain widely different emissions compounds, that need different treatment and require different operation parameter values in term of temperature, oxygen content,
15 absorbent content etc. in order to be effectively immobilised and/or destroyed in the preheater.
Besides from keeping the temperature in the preheater at the location of introduction of the second source exhaust gases into the preheater about at least
20 700 °C, the retention time of the second source exhaust gases under such temperature conditions should preferable be at least 0.5 second, most preferably at least 1 second in order to obtain most effective burning of the combustible emission compounds contained in the second source exhaust gases. The second source exhaust gases should contain sufficient oxygen to ensure
25 effective burning of the combustible emission compounds in the mixed gas stream in the preheater, however should the oxygen content of the mixed gas stream in the preheater at the location of introduction of the second source exhaust gases at some time during operation be below 2 % additional oxygen may be added.
30
The amount of alkaline dust present in the preheater and originating from the calciner should under normal operation conditions be sufficient to effectively scrub the acidic emission compounds, being S02/S03, HCI and H2S. However,
should the content of such alkaline dust for some reason be to low additional alkaline dust may be added.
The invention will now be described in further details with reference to the drawing, being diagrammatical, and where
Fig. 1 shows a plant for production of cement clinker according to the invention. In Fig. 1 is shown a plant for production of cement clinker comprising a cyclone preheater 1 , a calciner 3 with a separation cyclone 3a, a rotary kiln 5 and a cooler 7. Further, the shown plant comprises a milling department 9 for grinding and possibly drying cement raw materials, a waste material fuel preparation department 1 1 , a coal milling department 13 and a kiln bypass 15.
During operation of the plant cement raw material prepared in the milling department 9 is introduced into the cyclone preheater 1 via a feed inlet F and preheated by travelling down through the preheater 1 in counter flow to hot exhaust gases coming from the calciner 3, calcined in the calciner 3 suspended in hot exhaust gases from the rotary kiln 5 and possible subjected to additional fuel being fed into the calciner 3 via a burner 4 and coming from either the waste fuel preparation department 1 1 or the coal milling department 13, burned into cement clinker in the rotary kiln 5 subject to heat exchange with hot gases form by means of a burner installation 6 being supplied with fuel also from either the waste material fuel preparation department 1 1 or the coal milling department 13, and cooled in a cooler 7. The gases are drawn through the plant via a fan 17. Further, a proportion of the exhaust gases leaving the rotary kiln is extracted from the main flow via the kiln bypass 15 and treated in per se known way in order to extract unwanted volatile components, such as chloride, alkali and sulphur from the plant. In order to control the second source exhaust gas emissions originating from different second sources, such as, but not limited to, the cement raw material milling department 9, the waste fuel preparation department 1 1 , the coal milling departments 13 or the kiln bypass 15 in way which has minimum negative impact
on the heat consumption of the kiln system and which does not increase the gas flow through the rotary kiln 5 kiln and calciner 3 it is suggested according to the present invention to introduce such second source exhaust gases into the preheater 1 at a location 20 after the calciner 3 as viewed in the direction of movement of the gases from the calciner 3, preferably after the separation cyclone 3a being connected to the calciner, where the temperature is kept about at least 700 °C.
In this way the relative cold exhaust gases from the secondary sources 9, 1 1 , 13, 15 are not passed through the kiln 5 or calciner 3, thus minimizing the negative impact on the heat consumption of the kiln system, while the combustible emission compounds, being organic compounds, carbon monoxide, ammonia, etc., are still effectively combusted in the preheater 1 and the acidic emission compounds, being S02/S03, HCI, H2S, are effectively scrubbed by reacting with the alkaline dust present in the preheater 1 .
Besides from keeping the temperature in the preheater 1 at the location 20 of introduction of the second source exhaust gases into the preheater 1 about at least 700 °C, the retention time of the second source exhaust gases under such temperature conditions should preferable be at least 0.5 second, most preferably at least 1 second in order to ensure effective burning of the combustible emission compounds contained in the second source exhaust gases. The retention time of the second source exhaust gases may be determined by selecting a proper cross section area at the location 20 of introduction of the second source exhaust gases into the preheater 1 . The required oxygen to ensure burning of the combustible emission compounds in the mixed gas stream in the preheater 1 is contained in the second source exhaust gases, however should the oxygen content of the mixed gas stream in the preheater at the location 20 of introduction of the second source exhaust gases at some time during operation be below 2 % additional oxygen may be added.
The amount of alkaline dust present in the preheater 1 and originating from the calciner 3 should under normal operation conditions be sufficient to effectively
scrub the acidic emission compounds, being S02/S03, HCI and H2S. However, should the content of such alkaline dust for some reason be to low additional alkaline dust may be added.
Claims
1 . A method for manufacturing cement clinker, where cement raw materials are preheated in a preheater (1 ), calcined in a calciner (3) being connected to a separation cyclone (3a), burned into cement clinker in a kiln (5) and cooled in a clinker cooler (7), and where second source exhaust gases are produced in second source equipment (9, 1 1 , 13, 15) and introduced into the preheater (1 ) at a location (20) after the calciner (3) as viewed in the direction of movement of the gases from the calciner (3), characterized in that the temperature in the preheater (1 ) at the location of introduction (20) of the second source exhaust gases into the preheater (1 ) is kept about at least 700 °C.
2. A method according to claim 1 , characterized in that second source exhaust gases are introduced into the preheater (1 ) at a location after the separation cyclone (3a) being connected to the calciner (3) as viewed in the direction of movement of the gases from the calciner (3).
3. A method according to claim 1 , characterized in that the retention time of the second source exhaust gases under such temperature conditions is at least 0.5 second, preferably at least 1 second.
4. A method according to claim 1 , characterized in that additional oxygen is added at the location (20) of introduction of the second source exhaust gases in the preheater (1 ).
5. A method according to claim 1 , characterized in that additional alkaline dust is added at the location (20) of introduction of the second source exhaust gases in the preheater (1 )..
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DKPA201000879 | 2010-09-28 | ||
| DKPA201000879 | 2010-09-28 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO2012042418A1 true WO2012042418A1 (en) | 2012-04-05 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/IB2011/054004 WO2012042418A1 (en) | 2010-09-28 | 2011-09-13 | A method for manufacturing cement clinker |
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| WO (1) | WO2012042418A1 (en) |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2001019749A1 (en) * | 1999-09-16 | 2001-03-22 | Alstom (Switzerland) Ltd | Method of producing cement clinker from a cement raw mix and clean gas from coal |
| GB2396400A (en) * | 2000-02-08 | 2004-06-23 | Green Island Environmental Tec | Integrated cement production and waste disposal facility |
| WO2008032160A2 (en) * | 2006-09-14 | 2008-03-20 | Holcim Technology Ltd. | Method for pretreating charges contaminated with carbon carriers |
| US20100058963A1 (en) * | 2006-11-06 | 2010-03-11 | Sumitomo Osaka Cement Co., Ltd | Method for disposing of organic waste of high water content and disposal apparatus therefor |
-
2011
- 2011-09-13 WO PCT/IB2011/054004 patent/WO2012042418A1/en active Application Filing
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2001019749A1 (en) * | 1999-09-16 | 2001-03-22 | Alstom (Switzerland) Ltd | Method of producing cement clinker from a cement raw mix and clean gas from coal |
| GB2396400A (en) * | 2000-02-08 | 2004-06-23 | Green Island Environmental Tec | Integrated cement production and waste disposal facility |
| WO2008032160A2 (en) * | 2006-09-14 | 2008-03-20 | Holcim Technology Ltd. | Method for pretreating charges contaminated with carbon carriers |
| US20100058963A1 (en) * | 2006-11-06 | 2010-03-11 | Sumitomo Osaka Cement Co., Ltd | Method for disposing of organic waste of high water content and disposal apparatus therefor |
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