EP2563735A1 - A plant for manufacturing cement - Google Patents

A plant for manufacturing cement

Info

Publication number
EP2563735A1
EP2563735A1 EP11714838A EP11714838A EP2563735A1 EP 2563735 A1 EP2563735 A1 EP 2563735A1 EP 11714838 A EP11714838 A EP 11714838A EP 11714838 A EP11714838 A EP 11714838A EP 2563735 A1 EP2563735 A1 EP 2563735A1
Authority
EP
European Patent Office
Prior art keywords
gases
duct
plant
cement
central outlet
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.)
Withdrawn
Application number
EP11714838A
Other languages
German (de)
French (fr)
Inventor
Karl Stromberg
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
FLSmidth AS
Original Assignee
FLSmidth AS
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by FLSmidth AS filed Critical FLSmidth AS
Publication of EP2563735A1 publication Critical patent/EP2563735A1/en
Withdrawn legal-status Critical Current

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
    • 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
    • C04B7/60—Methods for eliminating alkali metals or compounds thereof, e.g. from the raw materials or during the burning process; methods for eliminating other harmful components
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D17/00—Arrangements for using waste heat; Arrangements for using, or disposing of, waste gases
    • F27D17/008—Arrangements for using waste heat; Arrangements for using, or disposing of, waste gases cleaning gases

Definitions

  • the present invention relates to a plant for manufacturing cement, which plant comprises a preheater for preheating cement raw materials suspended in gases, a bottom cyclone for separating the preheated cement raw materials and the gases, said cyclone having a central outlet duct for separated gases, a kiln for burning the calcined cement raw material into cement clinker, as well as a bypass duct for removing volatile components, such as chloride, alkali and sulphur, from the cement manufacturing plant, which bypass duct is located after the bottom cyclone viewed in the direction of movement of the gases.
  • Cement manufacturing plants of the aforementioned kind are well known.
  • volatile components such as chloride, alkali and sulphur
  • KCl One of the most common chloride compounds circulating in the kiln system is KCl.
  • the known plants using a bypass duct which is located after the bottom cyclone viewed in the direction of movement of the gases, divert a portion of the exhaust gases from the bottom cyclone, typically up to 10 per cent of the exhaust gases, thereby ensuring continuous extraction of volatile components from the cement manufacturing plant.
  • the exhaust gases are extracted via an opening in the wall of the central outlet duct into the bypass duct, which is mounted on the central outlet duct and terminates at the perimeter of the inner side of the wall of the central outlet duct.
  • the extracted exhaust gases are typically cooled in a separate chamber by the application of air and/or water to a temperature which is lower than the condensation temperature of the volatile components, thereby allowing the volatile components to be separated in solid form from the exhaust gases, for subsequent disposal or application in the finished cement or for other purposes.
  • the main disadvantage of the known plants is that the extracted exhaust gases due the low efficiency of the bottom cyclone contain a considerable amount of dust, which is either lost from the process or has to be re-entered into the plant after being separated from the gas. This is due to the fact that the gas/material suspension in the central outlet duct leaving the bottom cyclone is still swirling with rather high rotational velocity at the point of extraction via the bypass, thus the dust concentration is highest near the perimeter of the central outlet duct.
  • the dust problem might be solved at least partly by replacing the bottom cyclone with a high efficient cyclone, however such solution is not attractive as the pressure loss over the cyclone would then increase considerably.
  • this is achieved by a plant of the kind mentioned in the introduction, and being characterized in that the bypass duct extends into the central area of the central outlet duct.
  • the exhaust gases extracted through the bypass duct contain a significant smaller amount of dust and also that the entrained dust constitutes the finest fraction of the dust leaving the bottom cyclone with the exhaust gases. This is due to the fact that the dust concentration at the point of extraction via the bypass due to the swirling action of the exhaust gases is lowest in the central area of the central outlet duct.
  • bypass duct terminates in the central outlet duct in close vicinity to the bottom cyclone.
  • the bypass duct may extend under an inclined angel or vertically into the central outlet duct.
  • the inner free end of the bypass duct is constituted of a section having a centre line being parallel to the centre line of the central outlet duct.
  • Fig. 1 shows an embodiment of a cement manufacturing plant according to the invention.
  • Fig. 1 a plant for manufacturing cement clinker, which plant comprises a cyclone preheater 1, a calciner 3 with a bottom cyclone 11 having a central outlet duct 6 for separated gases, a rotary kiln 5 and a clinker cooler 7.
  • Cement raw materials are introduced via an inlet F in the inlet duct to the uppermost cyclone stage of the cyclone preheater 1, being preheated, calcined and burned into clinker by being transported first through the preheater 1, the calciner 3, and then through the rotary kiln 5 in counter flow to hot exhaust gases which are formed at, respectively, a burner 8 in the rotary kiln 5 and a burner 9 in the calciner 3, and combustion air which is introduced to the calciner 3 via a duct 10, and being drawn through the preheater string 1 by the application of a not shown fan.
  • the burned clinker is subsequently cooled in the clinker cooler 7 by the application of cooling air.
  • the shown plant also comprises a bypass installation 12 for removing volatile components, such as chloride, alkali and sulphur, from the cement manufacturing plant.
  • the bypass installation 12 is located after the bottom cyclone 11 and connected to the central outlet duct 6 in order to minimize the amount of calcined raw material entrained in the extracted gas stream.
  • the shown bypass comprises a bypass duct 14, a mixing chamber 13 for extracting and cooling a portion of the gases from the calciner 3, a conditioning tower 15 for additional cooling of the gases, a filter 16 for separating dust with a high content of chloride, alkali and/or sulphur, as well as a fan 17 for drawing the gases through the mentioned bypass.
  • the bypass duct 14 extends into the central area of the central outlet duct 6. Due to the swirling action of the exhaust gases the dust concentration is lowest in the central area of the central outlet duct 6 and thus the exhaust gases extracted through the bypass duct 14 contain a significant smaller amount of dust and also that the entrained dust constitutes the finest fraction of the dust leaving the bottom cyclone 11 with the exhaust gases.
  • bypass duct 14 terminates in the central outlet duct 6 in close vicinity to the bottom cyclone 11. This is to utilize the swirling action of the exhaust gases leaving the bottom cyclone 11 in best possible way.
  • the bypass duct 14 may, as shown, extend under an inclined angel into the central outlet duct 6.
  • a vertical bypass duct may be used, if coating and blockage problems occur in the bypass duct.
  • the inner free end of the bypass duct 14 is constituted of a section 14a having a centre line being parallel to the centre line of the central outlet duct.

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Ceramic Engineering (AREA)
  • Environmental & Geological Engineering (AREA)
  • Organic Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Public Health (AREA)
  • Health & Medical Sciences (AREA)
  • Structural Engineering (AREA)
  • Materials Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Biodiversity & Conservation Biology (AREA)
  • Toxicology (AREA)
  • Ecology (AREA)
  • Environmental Sciences (AREA)
  • Furnace Details (AREA)
  • Curing Cements, Concrete, And Artificial Stone (AREA)

Abstract

Described is a plant for manufacturing cement, which plant comprises a preheater (1) for preheating cement raw materials suspended in gases, a bottom cyclone (11) for separating the preheated cement raw materials and the gases, said cyclone (11) having a central outlet duct (6) for separated gases, a kiln (5) for burning the calcined cement raw material into cement clinker, as well as a bypass duct (14) for removing volatile components, such as chloride, alkali and sulphur, from the cement manufacturing plant, which bypass duct (14) is located after the bottom cyclone (11) viewed in the direction of movement of the gases. The plant is peculiar in that the bypass duct (14) extends into the central area of the central outlet duct (6). It is hereby obtained, that the exhaust gases extracted through the bypass duct (14) contain a significant smaller amount of dust and also that the entrained dust constitutes the finest fraction of the dust leaving the bottom cyclone (11) with the exhaust gases. This is due to the fact that the dust concentration at the point of extraction via the bypass due to the swirling action of the exhaust gases is lowest in the central area of the central outlet duct.

Description

    A PLANT FOR MANUFACTURING CEMENT
  • The present invention relates to a plant for manufacturing cement, which plant comprises a preheater for preheating cement raw materials suspended in gases, a bottom cyclone for separating the preheated cement raw materials and the gases, said cyclone having a central outlet duct for separated gases, a kiln for burning the calcined cement raw material into cement clinker, as well as a bypass duct for removing volatile components, such as chloride, alkali and sulphur, from the cement manufacturing plant, which bypass duct is located after the bottom cyclone viewed in the direction of movement of the gases.
  • Cement manufacturing plants of the aforementioned kind are well known. During manufacturing of cement different types and compositions of volatile components, such as chloride, alkali and sulphur, will often be introduced together with the cement raw materials and the fuel. These volatile components will circulate in the kiln system of the plant between the burning zone in which they undergo evaporation and the preheater zone in which they undergo condensation, and may cause clogging and unsteady kiln operation. One of the most common chloride compounds circulating in the kiln system is KCl.
  • The known plants using a bypass duct, which is located after the bottom cyclone viewed in the direction of movement of the gases, divert a portion of the exhaust gases from the bottom cyclone, typically up to 10 per cent of the exhaust gases, thereby ensuring continuous extraction of volatile components from the cement manufacturing plant. In the known plants the exhaust gases are extracted via an opening in the wall of the central outlet duct into the bypass duct, which is mounted on the central outlet duct and terminates at the perimeter of the inner side of the wall of the central outlet duct. Then the extracted exhaust gases are typically cooled in a separate chamber by the application of air and/or water to a temperature which is lower than the condensation temperature of the volatile components, thereby allowing the volatile components to be separated in solid form from the exhaust gases, for subsequent disposal or application in the finished cement or for other purposes. The main disadvantage of the known plants is that the extracted exhaust gases due the low efficiency of the bottom cyclone contain a considerable amount of dust, which is either lost from the process or has to be re-entered into the plant after being separated from the gas. This is due to the fact that the gas/material suspension in the central outlet duct leaving the bottom cyclone is still swirling with rather high rotational velocity at the point of extraction via the bypass, thus the dust concentration is highest near the perimeter of the central outlet duct. The dust problem might be solved at least partly by replacing the bottom cyclone with a high efficient cyclone, however such solution is not attractive as the pressure loss over the cyclone would then increase considerably.
  • It is the object of the present invention to provide a plant for manufacturing cement by means of which the aforementioned disadvantages are eliminated or significantly reduced.
  • According to the invention this is achieved by a plant of the kind mentioned in the introduction, and being characterized in that the bypass duct extends into the central area of the central outlet duct.
  • It is hereby obtained, that the exhaust gases extracted through the bypass duct contain a significant smaller amount of dust and also that the entrained dust constitutes the finest fraction of the dust leaving the bottom cyclone with the exhaust gases. This is due to the fact that the dust concentration at the point of extraction via the bypass due to the swirling action of the exhaust gases is lowest in the central area of the central outlet duct.
  • In order to utilize the centrifugal forces due to the swirling action of the exhaust gases leaving the bottom cyclone in best possible way it is preferred that the bypass duct terminates in the central outlet duct in close vicinity to the bottom cyclone.
  • The bypass duct may extend under an inclined angel or vertically into the central outlet duct. By using a vertical bypass duct coating and blockage problems in the bypass duct may be avoid, however it would in most cases required a much longer duct as compared to the inclined duct solution.
  • Further, it is preferred that the inner free end of the bypass duct is constituted of a section having a centre line being parallel to the centre line of the central outlet duct.
  • The invention will now be explained in further details with reference to the drawing, being diagrammatical, and where
  • Fig. 1 shows an embodiment of a cement manufacturing plant according to the invention.
  • In Fig. 1 is seen a plant for manufacturing cement clinker, which plant comprises a cyclone preheater 1, a calciner 3 with a bottom cyclone 11 having a central outlet duct 6 for separated gases, a rotary kiln 5 and a clinker cooler 7. Cement raw materials are introduced via an inlet F in the inlet duct to the uppermost cyclone stage of the cyclone preheater 1, being preheated, calcined and burned into clinker by being transported first through the preheater 1, the calciner 3, and then through the rotary kiln 5 in counter flow to hot exhaust gases which are formed at, respectively, a burner 8 in the rotary kiln 5 and a burner 9 in the calciner 3, and combustion air which is introduced to the calciner 3 via a duct 10, and being drawn through the preheater string 1 by the application of a not shown fan. The burned clinker is subsequently cooled in the clinker cooler 7 by the application of cooling air. The shown plant also comprises a bypass installation 12 for removing volatile components, such as chloride, alkali and sulphur, from the cement manufacturing plant.
  • In the embodiment shown in Fig. 1, the bypass installation 12 is located after the bottom cyclone 11 and connected to the central outlet duct 6 in order to minimize the amount of calcined raw material entrained in the extracted gas stream. The shown bypass comprises a bypass duct 14, a mixing chamber 13 for extracting and cooling a portion of the gases from the calciner 3, a conditioning tower 15 for additional cooling of the gases, a filter 16 for separating dust with a high content of chloride, alkali and/or sulphur, as well as a fan 17 for drawing the gases through the mentioned bypass.
  • According to the invention the bypass duct 14 extends into the central area of the central outlet duct 6. Due to the swirling action of the exhaust gases the dust concentration is lowest in the central area of the central outlet duct 6 and thus the exhaust gases extracted through the bypass duct 14 contain a significant smaller amount of dust and also that the entrained dust constitutes the finest fraction of the dust leaving the bottom cyclone 11 with the exhaust gases.
  • As shown, the bypass duct 14 terminates in the central outlet duct 6 in close vicinity to the bottom cyclone 11. This is to utilize the swirling action of the exhaust gases leaving the bottom cyclone 11 in best possible way.
  • The bypass duct 14 may, as shown, extend under an inclined angel into the central outlet duct 6. Alternatively a vertical bypass duct may be used, if coating and blockage problems occur in the bypass duct.
  • Further, it may be advantageous if the inner free end of the bypass duct 14 is constituted of a section 14a having a centre line being parallel to the centre line of the central outlet duct.

Claims (5)

1. A plant for manufacturing cement, which plant comprises a preheater (1) for preheating cement raw materials suspended in gases, a bottom cyclone (11) for separating the preheated cement raw materials and the gases, said cyclone (11) having a central outlet duct (6) for separated gases, a kiln (5) for burning the calcined cement raw material into cement clinker, as well as a bypass duct (14) for removing volatile components, such as chloride, alkali and sulphur, from the cement manufacturing plant, which bypass duct (14) is located after the bottom cyclone (11) viewed in the direction of movement of the gases, characterized in that the bypass duct (14) extends into the central area of the central outlet duct (6).
A plant according to claim 1, characterized in that the bypass duct (14) terminates in the central outlet duct (6) in close vicinity to the bottom cyclone (11).
A plant according to claim 1 or 2, characterized in that the bypass duct (14) extends under an inclined angel into the central outlet duct (6).
A plant according to claim 1 or 2, characterized in that the bypass duct (14) extend vertically into the central outlet duct (6).
A plant according to claim 1, characterized in that the inner free end of the bypass duct (14) is constituted of a section (14a) having a centre line being parallel to the centre line of the central outlet duct (6).
EP11714838A 2010-04-29 2011-03-17 A plant for manufacturing cement Withdrawn EP2563735A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DKPA201000381 2010-04-29
PCT/IB2011/051115 WO2011135468A1 (en) 2010-04-29 2011-03-17 A plant for manufacturing cement

Publications (1)

Publication Number Publication Date
EP2563735A1 true EP2563735A1 (en) 2013-03-06

Family

ID=44169122

Family Applications (1)

Application Number Title Priority Date Filing Date
EP11714838A Withdrawn EP2563735A1 (en) 2010-04-29 2011-03-17 A plant for manufacturing cement

Country Status (2)

Country Link
EP (1) EP2563735A1 (en)
WO (1) WO2011135468A1 (en)

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH09227184A (en) * 1996-02-21 1997-09-02 Chichibu Onoda Cement Corp Treating of exhaust gas from cement kiln and apparatus therefor
JP3125248B2 (en) * 1997-07-17 2001-01-15 太平洋セメント株式会社 Exhaust gas cooling method and device in kiln bypass
DK200800141A (en) * 2008-02-01 2009-08-02 Smidth As F L Cement manufacturing plant

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO2011135468A1 *

Also Published As

Publication number Publication date
WO2011135468A1 (en) 2011-11-03

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