CA1162402A - Calcining a sludge comprising calciumcarbonate - Google Patents
Calcining a sludge comprising calciumcarbonateInfo
- Publication number
- CA1162402A CA1162402A CA000376832A CA376832A CA1162402A CA 1162402 A CA1162402 A CA 1162402A CA 000376832 A CA000376832 A CA 000376832A CA 376832 A CA376832 A CA 376832A CA 1162402 A CA1162402 A CA 1162402A
- Authority
- CA
- Canada
- Prior art keywords
- temperature
- granulated material
- fluidized
- stages
- organic matter
- 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
- 239000010802 sludge Substances 0.000 title claims abstract description 23
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 title claims abstract description 22
- 238000001354 calcination Methods 0.000 title claims abstract description 22
- 229910000019 calcium carbonate Inorganic materials 0.000 title claims abstract description 11
- 229960003563 calcium carbonate Drugs 0.000 title 1
- 235000010216 calcium carbonate Nutrition 0.000 title 1
- 239000008187 granular material Substances 0.000 claims abstract description 50
- 239000005416 organic matter Substances 0.000 claims abstract description 30
- 239000002245 particle Substances 0.000 claims abstract description 13
- 238000002485 combustion reaction Methods 0.000 claims abstract description 6
- 238000009434 installation Methods 0.000 claims description 30
- 238000000034 method Methods 0.000 claims description 22
- 230000004888 barrier function Effects 0.000 claims description 11
- 239000002912 waste gas Substances 0.000 claims description 10
- 239000000463 material Substances 0.000 claims description 9
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims description 6
- 239000007789 gas Substances 0.000 claims description 6
- 238000005469 granulation Methods 0.000 claims description 6
- 230000003179 granulation Effects 0.000 claims description 6
- 238000001035 drying Methods 0.000 claims description 4
- 229910002092 carbon dioxide Inorganic materials 0.000 claims description 3
- 239000001569 carbon dioxide Substances 0.000 claims description 3
- 238000000354 decomposition reaction Methods 0.000 claims description 3
- 239000000446 fuel Substances 0.000 claims description 3
- 238000005192 partition Methods 0.000 claims description 3
- 238000011084 recovery Methods 0.000 claims description 2
- 239000002918 waste heat Substances 0.000 claims 3
- 238000002309 gasification Methods 0.000 abstract 1
- 239000000428 dust Substances 0.000 description 17
- 238000010438 heat treatment Methods 0.000 description 6
- 238000004519 manufacturing process Methods 0.000 description 6
- 239000002699 waste material Substances 0.000 description 4
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 239000000571 coke Substances 0.000 description 2
- 235000013379 molasses Nutrition 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical group [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- ODINCKMPIJJUCX-UHFFFAOYSA-N Calcium oxide Chemical compound [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- 235000019738 Limestone Nutrition 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- 229910001861 calcium hydroxide Inorganic materials 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000020169 heat generation Effects 0.000 description 1
- 239000006028 limestone Substances 0.000 description 1
- 239000006188 syrup Substances 0.000 description 1
- 235000020357 syrup Nutrition 0.000 description 1
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
- C04B2/00—Lime, magnesia or dolomite
- C04B2/10—Preheating, burning calcining or cooling
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J6/00—Heat treatments such as Calcining; Fusing ; Pyrolysis
- B01J6/001—Calcining
- B01J6/004—Calcining using hot gas streams in which the material is moved
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
- B01J8/18—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with fluidised particles
- B01J8/24—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with fluidised particles according to "fluidised-bed" technique
- B01J8/36—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with fluidised particles according to "fluidised-bed" technique with fluidised bed through which there is an essentially horizontal flow of particles
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W10/00—Technologies for wastewater treatment
- Y02W10/40—Valorisation of by-products of wastewater, sewage or sludge processing
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Thermal Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Physics & Mathematics (AREA)
- Ceramic Engineering (AREA)
- Combustion & Propulsion (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Treatment Of Sludge (AREA)
- Devices And Processes Conducted In The Presence Of Fluids And Solid Particles (AREA)
- Processing Of Solid Wastes (AREA)
- Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
- Gasification And Melting Of Waste (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A sludge containing calcium carbonate to be calcined is granulated, and the granulated material obtained from the sludge is clacined in a fluidized state in two or more temperature stages, advantageously on combustion of organic matter, whereby the temperature of granulated matter of the highest temperature stage is equal to or greater than 880°C, whilst the preceding temperature stages have a temperature of granulated matter of less than 880°C. In this way, the gasification occurring on calcination takes place gradually in the particles of granular material, and the particles of granular material remain intact.
A sludge containing calcium carbonate to be calcined is granulated, and the granulated material obtained from the sludge is clacined in a fluidized state in two or more temperature stages, advantageously on combustion of organic matter, whereby the temperature of granulated matter of the highest temperature stage is equal to or greater than 880°C, whilst the preceding temperature stages have a temperature of granulated matter of less than 880°C. In this way, the gasification occurring on calcination takes place gradually in the particles of granular material, and the particles of granular material remain intact.
Description
1 ~ 6~40~
The invention relates to a method for calcining a sludge containing clacium carbonate, whereby the sludge is previously granulated.
The invention also relates to a device for carrying out this process.
In industrial processes, for example in the maufacture of soda, or in asugar factory in purifying syrup,or in the manufacture of celIulose, a sludge or waste liquor containing calcium carbonate is frequently ob-t~ined as a waste product. In order to avoid the depositon of this sludge and reduce the consumption of limestone, it is suggested that the sludge or waste liquor be calcined.
In the known methods for calcining sludge, this is brought into a solidform, for example granulated. On heating up to the calcination tem~erature, so much dust is produced, however, that the apparatus necessary for heat recovery is clogged after a very short time.
I~le invention is based on the new findings, that gas formation in heating up granulated material damages the individual granular particles. The inventors have accordingly posed themselves the problem of enabling the granulated material to be heated up in a way which will preserve the granular particles as much as possible.
' g~
0 ~
~ his problem is solved b~ the method according to the invention in that the granulated material obtained from the sludge is calcined in a fluidized state in two or more temperature stages, the temperature stage with the highest temperature being expediently selected such that it corresponds to the re~uired decomposition degree of calcium carbonate.
Thus, the invention provides a method for calcining a sludge containing calcium carbonate comprising the steps of granulating the sludge, and calcining the granulated material in a fluidized state in at least two stages having different temperatures, wherein the material moves se~uentially in a fluidized state through said stages in the horizontal direction and the temperature increases from one stage to at least one following stage in the direction of said movement, the temperature of the stage having the highest temperature being selected to afford a specified degree of decomposition of calcium carbonate and being at least 880C, and the temperature of each preceding stage being below 880C.
It has been shown that the output within an available period of time assumes a practicably usable value when this highest temperature stage is at 880C or above, whereby the other temperatures are correspondingly graduated and lie below 880C.
The particles of granulated material are particularly preserved if the granulate temperature of the temperatuge stages increases from stage to stage in the direction of movement of the granulated material.
Preferably, calcination takes place on combustion of organic matter. The molasses from sugar factories already contain
The invention relates to a method for calcining a sludge containing clacium carbonate, whereby the sludge is previously granulated.
The invention also relates to a device for carrying out this process.
In industrial processes, for example in the maufacture of soda, or in asugar factory in purifying syrup,or in the manufacture of celIulose, a sludge or waste liquor containing calcium carbonate is frequently ob-t~ined as a waste product. In order to avoid the depositon of this sludge and reduce the consumption of limestone, it is suggested that the sludge or waste liquor be calcined.
In the known methods for calcining sludge, this is brought into a solidform, for example granulated. On heating up to the calcination tem~erature, so much dust is produced, however, that the apparatus necessary for heat recovery is clogged after a very short time.
I~le invention is based on the new findings, that gas formation in heating up granulated material damages the individual granular particles. The inventors have accordingly posed themselves the problem of enabling the granulated material to be heated up in a way which will preserve the granular particles as much as possible.
' g~
0 ~
~ his problem is solved b~ the method according to the invention in that the granulated material obtained from the sludge is calcined in a fluidized state in two or more temperature stages, the temperature stage with the highest temperature being expediently selected such that it corresponds to the re~uired decomposition degree of calcium carbonate.
Thus, the invention provides a method for calcining a sludge containing calcium carbonate comprising the steps of granulating the sludge, and calcining the granulated material in a fluidized state in at least two stages having different temperatures, wherein the material moves se~uentially in a fluidized state through said stages in the horizontal direction and the temperature increases from one stage to at least one following stage in the direction of said movement, the temperature of the stage having the highest temperature being selected to afford a specified degree of decomposition of calcium carbonate and being at least 880C, and the temperature of each preceding stage being below 880C.
It has been shown that the output within an available period of time assumes a practicably usable value when this highest temperature stage is at 880C or above, whereby the other temperatures are correspondingly graduated and lie below 880C.
The particles of granulated material are particularly preserved if the granulate temperature of the temperatuge stages increases from stage to stage in the direction of movement of the granulated material.
Preferably, calcination takes place on combustion of organic matter. The molasses from sugar factories already contain
-2 1 J ~2~0~
organic matter. Preferably, however, organic matter can be admixed at least with the fluidized granulated material in the temperature stage with the highest temperature. On the other hand, it is preferable if at least in the temperature stage with the lowest temperature, the organic matter contained in the granulated material serves solely as fuel for calcination.
Preferabl~, granulated material is also fed into the granulated material which is in a fluidized state, in further temperature stages following the temperature stage with the lowest temperature.
-2a-I J 62~02 On granulation and drying of the sludge preferably a temperature is used, whereby the organic matter is not yet converted into the gaseous state.
If the sludge which is to be calcined does not contain any organic matter, it is advantageous if for all temperature stages organic matter is admixed to the fluidized granulated material, sifted to a required size of granular particle.
Preferably, for the combustion of the organic matter, the operation is carried out stoichiometrically or with excess air. m e waste gas of t~ temperature stage operating with excess air is preferably drawn off separately from the waste gas from the remaining temperature stages.
It is advantageous if a fluidized bed installation is used for the process, which is subdivided into two or more stages in the direction of movement of the fluidized granulated material.
The fludized bed installation preferably has one or more barriers subdividing the fluidized ganulated material, which advantageously are in the form of a lower course barrier.
It is advantageous if the fluidized bed installation has an air supply box ccmmon to all temperature stages, whilst regulators are provided for the addition of the granulated material and)or the organic matter into the fluidized bed installation can have at least one partition separating two temperature stages. However, the air supply box of the fluidized bed installation can also be subdivided into stages of different air temperature.
1 1 82~02 In the drawing on the basis of which the invention is explained in more detail, example embodlments of the object of the invention are represented in a simplified form showing:
Fig. 1 A diagram of a calcination plant Fig. 2 and 3 a further form of embodiment, respectively, for the fluidized bed installation according to Fig. 1.
e plant shown in Fig. 1 for calcination of a sludge containing calcium carbonate has a delivery pipe 1 for the sludge,eg. the molasses originating from the manufacture of sugar. Ihe sludge is granulated in a granulator 2. The granulated material is dried in a drier 3 and arrives into a sifter 5 via an elevator 4. The sifted portion of the granulated material passes into a silo 6 and is introduced into a fluidized be~ installation 9 by a dosing device 7 via pipes 8.
I'he granulated material, which is calcined to caustic lime in the fluidized bed installation, is fed through a further dosing device 10 to a fluidized bed cooler 11, and after cooling is returned to the sugar manufacturing plant for re-use by means of a pipe 12.
.
Operating air is fed in through a pipe 13, is heated up in a heat exchanger 14 and is passed into the air supply box 15 of the fluidized bed installation 9. The waste gas containing carbon dioxide frcm the fluidized bed drier 9, arrives into the heat exchanger 14 via a dust separator 16, and finally via a further heat exchanger 17 and a dust separator 18 into a pipe 19, which returns the gas for re-use in the sugar manufacturing plant.
~16~0~
Organic matter, waste coke in the example embodm ent, arrives into the fluidized bed installation 9 via a silo 20 and a dosing device 21.
'me drier 3 is in the form of a fluidized ~ed drier. It has a heating coil 22 lying in the fluidized bed. The air supply to the air supply b3x of the drier 3 passes through a heat exchanger 23. 'me heating coil 22 and the heat exchanger 23 are heated through a steam pipe 24.
A dust separator 25 is provided for the waste gases of the fluidized bed cooler 11, fram which the exhaust air escapes via a pipe 26. The dust from the dust separator 25 arrives into pipe 12.
m e exhaust air of the drier 3 passes into the open via a dust separator 27. m e dust which is separated in the dust separator 27 arrives into the granulation installation 2. m e coarse and fine material, separated in the sifter 5, also arrives into the granulator 2 via pipes 28 or 2g.
m e granulated material to be treated i5 calcined in the fluidised bed installation 9 in at least two ie. three temperature stages 30,31 and 32 on combustion of the organic matter contained in the granulated material and in the third temperature stage 32 on ccmbustion of the organic matter introduced via the dosing device 21.
m e drier 3 is in the form of a fluidized bed drier. It has a heating coil 22 lying in the fluidized bed. The air supply to the air supply box of the drier 3 passes through a heat exchanger 23. me heating coil 22 and the heat exchanger 23 are heated through a steam pipe 24.
A dust separator 25 is provided for the waste gases of the fluidized bed cooler 11, from which the exhaust air escapes via a pipe 26. m e dust from the dust separator 25 arrives into pipe 12.
1 3 62~2 The exhaust air of the drier 3 passes into the open via a dust separator 27. The dust which is separated in the dust separator 27 arrives into the granulation isntallation 2. The coarse and fine material separated in the sifter 5, also arrives into the granulator 2 via pipes 28 or 29.
The granulated material to be treated is calcined in the fluidized bed installation 9 in at least two, ie. three temperature stages 30,31 and 32 on ccmbustion of the organic matter contained in the granulated material, and in the third temperature stage 32 on ccmbustion of the organic matter introduced via the dosing device 21.
m e temperature of the highest temperature stage is to be selected such that it corresponds to the required degree of deccmposition of calcium carkonate. The relevent relationship is kncwn to the specialist in the art.
It was shcwn that a good output can be achieved if the highest temperature stage is selected at at least 880 C, the temperature required for complete calcination.
In the example embcdiment described, the highest tempera.ure stage is at 930C. The preceding temperature stages 31 and 30 in the direction of movement of the gra~ulated material to be treated, have a temperature i 1 ~2~0~
of less than 880C ie. temperature stage 31 has a temperature of 860 C, and temperature stage 30 has a temperature of 830C. The temperature of the temperature stages therefore increases frcm stage to stage in the direction of movement of the granulated material.
In the fluidized bed installation 9, the calcination is therefore subdivided into steps, whereby the generation of gas in the granular particles is decelerated such that the particles are not destroyed. Furthermore, the granular particles are, as is well known, treated extremely carefully in a fluidized bed. merefore, crushing of the particles does not result and there is scarcely a formation of dust.
The pipe 8 not only feeds granulated material to be treated into the first tempexature stage 30 of the fluidized bed installation, but also into the second temperature stage 31. Hcwever, no fresh granulated material is fed into the final température stage 32, so that no incompletely calcinated granular particles can leave -the fluidized bed installation 9. To regulate the the degree of calcination in the individual temperature stages, however, organic matter (coke) could be fed via the dosing device 21 into the second temperature stage 31 or also into the first temperature stage 30.
In order that all organic matter contained in the granulated material can be fed, still unburned, into the fluidized bed installation 9, on granulation and drying of the sludge and on drying of the granulated material in the drier 3, a temperature is used in which the organic matter is not yet converted into the gaseous state,ie. a temperature of 60 - 200& .
Regulation of the fluidized bed installation 9 beccmes very simple if the operation for cQmbustion of the organic matter is carried out with excess air, the supply of air to the air supply box 15 is kept constant and the feeding in of granular material through the dosing device 7 and the pipe 8 is likewise kept constant. By regulating the dosing device 21 for the organic matter to be introduced in the final temperature stage 32, the I 1 6~02 degree of calcination of the granulated material leaving the fluidized bed installation 9, for example the ccmplete recalcination, can be regulated.
In the example embodiment represented in Fig. 2, the exhaust chamber ofthe fluidized bed installation 9 is also subdivided. The waste gases of the third or fLnal temperature stage 32 leave the fluidized bed installation through a separate pipe 33, with a greater proportion of air, whilst the waste gases of the temperature stages 30 and 31 with the least proportion of foreign matter and correspondingly large proportion of carbon dioxide, are passed into the dust separator 16 via a pipe 34.
me fluidized bed installation 9 shcwn in Fi~. 3 serves for the calcination of a sludge containing calcium carbonate, which does not contain any organic matter, for example, for the sludge containing calcium carbonate fram the manufacture of soda. The dosing device 21 feeds the organic matter necessary for heat generation, via a pipe 35 into all temperature stages 30,31 and 32.
In the example embcdiments the temperature stages 30,31 and 32 are constructed such that the fluidized bed installation has one or more,ie.
two barriers 36,37, subdividing the flcw of the fluidized granulated material. As is evidient for example fram Fig. 1, the barriers are in the form of a lower course barrier, ie. they allow a through flcw. m e con-struction as lower course barriers pernits a thermal flow from the temperature stages of higher temperature into temperature stages of lower temperature, ie. against the flow of the fluidized granulated material.
me barrier 37 according to Fig. 2 is extended upwards to the cover of the exhaust gas box of the fluidized bed installation 9. The extension forms a partition in the exhaust gas box.
organic matter. Preferably, however, organic matter can be admixed at least with the fluidized granulated material in the temperature stage with the highest temperature. On the other hand, it is preferable if at least in the temperature stage with the lowest temperature, the organic matter contained in the granulated material serves solely as fuel for calcination.
Preferabl~, granulated material is also fed into the granulated material which is in a fluidized state, in further temperature stages following the temperature stage with the lowest temperature.
-2a-I J 62~02 On granulation and drying of the sludge preferably a temperature is used, whereby the organic matter is not yet converted into the gaseous state.
If the sludge which is to be calcined does not contain any organic matter, it is advantageous if for all temperature stages organic matter is admixed to the fluidized granulated material, sifted to a required size of granular particle.
Preferably, for the combustion of the organic matter, the operation is carried out stoichiometrically or with excess air. m e waste gas of t~ temperature stage operating with excess air is preferably drawn off separately from the waste gas from the remaining temperature stages.
It is advantageous if a fluidized bed installation is used for the process, which is subdivided into two or more stages in the direction of movement of the fluidized granulated material.
The fludized bed installation preferably has one or more barriers subdividing the fluidized ganulated material, which advantageously are in the form of a lower course barrier.
It is advantageous if the fluidized bed installation has an air supply box ccmmon to all temperature stages, whilst regulators are provided for the addition of the granulated material and)or the organic matter into the fluidized bed installation can have at least one partition separating two temperature stages. However, the air supply box of the fluidized bed installation can also be subdivided into stages of different air temperature.
1 1 82~02 In the drawing on the basis of which the invention is explained in more detail, example embodlments of the object of the invention are represented in a simplified form showing:
Fig. 1 A diagram of a calcination plant Fig. 2 and 3 a further form of embodiment, respectively, for the fluidized bed installation according to Fig. 1.
e plant shown in Fig. 1 for calcination of a sludge containing calcium carbonate has a delivery pipe 1 for the sludge,eg. the molasses originating from the manufacture of sugar. Ihe sludge is granulated in a granulator 2. The granulated material is dried in a drier 3 and arrives into a sifter 5 via an elevator 4. The sifted portion of the granulated material passes into a silo 6 and is introduced into a fluidized be~ installation 9 by a dosing device 7 via pipes 8.
I'he granulated material, which is calcined to caustic lime in the fluidized bed installation, is fed through a further dosing device 10 to a fluidized bed cooler 11, and after cooling is returned to the sugar manufacturing plant for re-use by means of a pipe 12.
.
Operating air is fed in through a pipe 13, is heated up in a heat exchanger 14 and is passed into the air supply box 15 of the fluidized bed installation 9. The waste gas containing carbon dioxide frcm the fluidized bed drier 9, arrives into the heat exchanger 14 via a dust separator 16, and finally via a further heat exchanger 17 and a dust separator 18 into a pipe 19, which returns the gas for re-use in the sugar manufacturing plant.
~16~0~
Organic matter, waste coke in the example embodm ent, arrives into the fluidized bed installation 9 via a silo 20 and a dosing device 21.
'me drier 3 is in the form of a fluidized ~ed drier. It has a heating coil 22 lying in the fluidized bed. The air supply to the air supply b3x of the drier 3 passes through a heat exchanger 23. 'me heating coil 22 and the heat exchanger 23 are heated through a steam pipe 24.
A dust separator 25 is provided for the waste gases of the fluidized bed cooler 11, fram which the exhaust air escapes via a pipe 26. The dust from the dust separator 25 arrives into pipe 12.
m e exhaust air of the drier 3 passes into the open via a dust separator 27. m e dust which is separated in the dust separator 27 arrives into the granulation installation 2. m e coarse and fine material, separated in the sifter 5, also arrives into the granulator 2 via pipes 28 or 2g.
m e granulated material to be treated i5 calcined in the fluidised bed installation 9 in at least two ie. three temperature stages 30,31 and 32 on combustion of the organic matter contained in the granulated material and in the third temperature stage 32 on ccmbustion of the organic matter introduced via the dosing device 21.
m e drier 3 is in the form of a fluidized bed drier. It has a heating coil 22 lying in the fluidized bed. The air supply to the air supply box of the drier 3 passes through a heat exchanger 23. me heating coil 22 and the heat exchanger 23 are heated through a steam pipe 24.
A dust separator 25 is provided for the waste gases of the fluidized bed cooler 11, from which the exhaust air escapes via a pipe 26. m e dust from the dust separator 25 arrives into pipe 12.
1 3 62~2 The exhaust air of the drier 3 passes into the open via a dust separator 27. The dust which is separated in the dust separator 27 arrives into the granulation isntallation 2. The coarse and fine material separated in the sifter 5, also arrives into the granulator 2 via pipes 28 or 29.
The granulated material to be treated is calcined in the fluidized bed installation 9 in at least two, ie. three temperature stages 30,31 and 32 on ccmbustion of the organic matter contained in the granulated material, and in the third temperature stage 32 on ccmbustion of the organic matter introduced via the dosing device 21.
m e temperature of the highest temperature stage is to be selected such that it corresponds to the required degree of deccmposition of calcium carkonate. The relevent relationship is kncwn to the specialist in the art.
It was shcwn that a good output can be achieved if the highest temperature stage is selected at at least 880 C, the temperature required for complete calcination.
In the example embcdiment described, the highest tempera.ure stage is at 930C. The preceding temperature stages 31 and 30 in the direction of movement of the gra~ulated material to be treated, have a temperature i 1 ~2~0~
of less than 880C ie. temperature stage 31 has a temperature of 860 C, and temperature stage 30 has a temperature of 830C. The temperature of the temperature stages therefore increases frcm stage to stage in the direction of movement of the granulated material.
In the fluidized bed installation 9, the calcination is therefore subdivided into steps, whereby the generation of gas in the granular particles is decelerated such that the particles are not destroyed. Furthermore, the granular particles are, as is well known, treated extremely carefully in a fluidized bed. merefore, crushing of the particles does not result and there is scarcely a formation of dust.
The pipe 8 not only feeds granulated material to be treated into the first tempexature stage 30 of the fluidized bed installation, but also into the second temperature stage 31. Hcwever, no fresh granulated material is fed into the final température stage 32, so that no incompletely calcinated granular particles can leave -the fluidized bed installation 9. To regulate the the degree of calcination in the individual temperature stages, however, organic matter (coke) could be fed via the dosing device 21 into the second temperature stage 31 or also into the first temperature stage 30.
In order that all organic matter contained in the granulated material can be fed, still unburned, into the fluidized bed installation 9, on granulation and drying of the sludge and on drying of the granulated material in the drier 3, a temperature is used in which the organic matter is not yet converted into the gaseous state,ie. a temperature of 60 - 200& .
Regulation of the fluidized bed installation 9 beccmes very simple if the operation for cQmbustion of the organic matter is carried out with excess air, the supply of air to the air supply box 15 is kept constant and the feeding in of granular material through the dosing device 7 and the pipe 8 is likewise kept constant. By regulating the dosing device 21 for the organic matter to be introduced in the final temperature stage 32, the I 1 6~02 degree of calcination of the granulated material leaving the fluidized bed installation 9, for example the ccmplete recalcination, can be regulated.
In the example embodiment represented in Fig. 2, the exhaust chamber ofthe fluidized bed installation 9 is also subdivided. The waste gases of the third or fLnal temperature stage 32 leave the fluidized bed installation through a separate pipe 33, with a greater proportion of air, whilst the waste gases of the temperature stages 30 and 31 with the least proportion of foreign matter and correspondingly large proportion of carbon dioxide, are passed into the dust separator 16 via a pipe 34.
me fluidized bed installation 9 shcwn in Fi~. 3 serves for the calcination of a sludge containing calcium carbonate, which does not contain any organic matter, for example, for the sludge containing calcium carbonate fram the manufacture of soda. The dosing device 21 feeds the organic matter necessary for heat generation, via a pipe 35 into all temperature stages 30,31 and 32.
In the example embcdiments the temperature stages 30,31 and 32 are constructed such that the fluidized bed installation has one or more,ie.
two barriers 36,37, subdividing the flcw of the fluidized granulated material. As is evidient for example fram Fig. 1, the barriers are in the form of a lower course barrier, ie. they allow a through flcw. m e con-struction as lower course barriers pernits a thermal flow from the temperature stages of higher temperature into temperature stages of lower temperature, ie. against the flow of the fluidized granulated material.
me barrier 37 according to Fig. 2 is extended upwards to the cover of the exhaust gas box of the fluidized bed installation 9. The extension forms a partition in the exhaust gas box.
Claims (21)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method for calcining a sludge containing calcium carbonate comprising the steps of granulating the sludge, and calcining the granulated material in a fluidized state in at least two stages having different temperatures, wherein the material moves sequentially in a fluidized state through said stages in the horizontal direction and the temperature increases from one stage to at least one following stage in the direction of said movement, the temperature of the stage having the highest temperature being selected to afford a specified degree of decomposition of calcium carbonate and being at least 880°C, and the temperature of each preceding stage being below 880°C.
2. A method according to claim 1, wherein the calcination takes place on combustion of organic matter.
3. A method according to claim 2, wherein at least in the temperature stage with the highest temperature, organic matter is admixed with the fluidized granulated material.
4. A method according to claim 2, wherein for all temperature stages organic matter is admixed with the fluidized granulated material, as fuel for calcination.
5. A method according to claim 2, wherein for the combustion of the organic matter, the operation is carried out stoichio-metrically or with excess air.
6. A method according to claim 2, wherein waste gas from the temperature stage with the highest temperature is drawn off separately from waste gas from the remaining temperature stages.
7. A method according to claim 2, wherein organic matter is contained in the granulated material.
8. A method according to claim 7, wherein at least in the temperature stage with the lowest temperature the organic matter contained in the granulated material serves solely as fuel for calcination.
9. A method according to claim 7, wherein on granulation and drying of the sludge a temperature is used at which the organic matter is not yet converted into the gaseous state.
10. A method according to claim 1, wherein granulated material is also fed into the fluidized granulation material in further temperature stages, following the temperature stage with the lowest temperature.
11. A method according to claim 1, wherein the granulated material, sifted to a required size of granular particles, is fed into the fluidized granulated material.
12. A method according to claim 11, wherein the remaining granulated material having a greater and a smaller size of granular particles than the sifted material is fed back to the material to be granulated.
13. A method according to claim 1, wherein calcinated granulated material is cooled down to its re-use temperature in a fluidized bed cooler and the waste heat of the fluidized bed cooler is used to dry the granulated material to be calcined.
14. A method according to claim 1, wherein waste gas containing carbon dioxide and produced through the calcination gives off heat, via a first heat exchanger, to the air to be added to the fluidized granulated material, and is then cooled down in a second heat exchanger, by waste heat recovery, to its re-use temperature.
15. A method according to claim 14, wherein the waste heat of the second heat exchanger is used, under indirect heat transfer, to dry the granulated material.
16. A device for carrying out the method according to claim 1, comprising a fluidized bed installation for producing a fluidized layer of granulated material, said fluidized bed installation being subdivided into at least two temperature stages.
17. A device according to claim 16, wherein one or more barriers are provided, subdividing the flow of the fluidized granulated material in the fluidized bed installation in its direction of movement.
18. A device according to claim 17, wherein the barrier or barriers are in the form of a lower course barrier.
19. A device according to claim 16, wherein an exhaust gas box is provided for the fluidized bed installation, said box having at least one partition separating two temperature stages.
20. A device according to claim 16, wherein the fluidized bed installation has an air supply box common to all temperature stages, and regulators for the supply box common to all temperature stages, and regulators for the supply of granulated material, and/or of organic matter into the fluidized granulated material.
21. A device according to claim 16, wherein the fluidized bed installation has an air supply box being subdivided into stages of different air temperature.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CH3902/80-5 | 1980-05-20 | ||
| CH390280A CH645083A5 (en) | 1980-05-20 | 1980-05-20 | METHOD AND DEVICE FOR RECALCINATING A SLAVE CONTAINING CALCIUM CARBONATE. |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1162402A true CA1162402A (en) | 1984-02-21 |
Family
ID=4265957
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000376832A Expired CA1162402A (en) | 1980-05-20 | 1981-05-04 | Calcining a sludge comprising calciumcarbonate |
Country Status (17)
| Country | Link |
|---|---|
| JP (1) | JPS5716714A (en) |
| AT (1) | AT383106B (en) |
| AU (1) | AU546179B2 (en) |
| BE (1) | BE888860A (en) |
| BR (1) | BR8102986A (en) |
| CA (1) | CA1162402A (en) |
| CH (1) | CH645083A5 (en) |
| DE (1) | DE3116572A1 (en) |
| DK (1) | DK219581A (en) |
| ES (1) | ES502303A0 (en) |
| FR (1) | FR2482946A1 (en) |
| GB (1) | GB2076308B (en) |
| IT (1) | IT1135838B (en) |
| LU (1) | LU83373A1 (en) |
| NL (1) | NL8102461A (en) |
| PL (1) | PL231238A1 (en) |
| ZA (1) | ZA812839B (en) |
Families Citing this family (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AT384204B (en) * | 1983-12-21 | 1987-10-12 | Af Processkonsult Ab | Method of fuelling a lime slurry calcining furnace with a solid fuel |
| CA1244855A (en) * | 1985-01-18 | 1988-11-15 | Kazuyuki Matsumoto | Robot arm drive apparatus of industrial robot |
| EP0789670B1 (en) * | 1995-04-11 | 2003-05-21 | Imerys Minerals Limited | Treatment of solid-containing material derived from effluent |
| GB9606638D0 (en) * | 1996-03-29 | 1996-06-05 | Ecc Int Ltd | Treatment of solid containing material derived from effluent |
| US20020079075A1 (en) | 1998-09-04 | 2002-06-27 | Imerys Minerals Limited | Treatment of solid containing material derived from effluent |
| DE19743742C2 (en) * | 1997-10-02 | 2001-08-23 | Sicowa Verfahrenstech | Process for making quicklime |
| EP2116294A1 (en) * | 2008-05-09 | 2009-11-11 | Claudius Peters Technologies GmbH | Calcination method and facility |
| US9289739B2 (en) | 2009-06-23 | 2016-03-22 | Chevron Philips Chemical Company Lp | Continuous preparation of calcined chemically-treated solid oxides |
| EP3221264B1 (en) * | 2014-11-18 | 2022-02-23 | Calix Limited | Process and apparatus for manufacture of calcined compounds for the production of calcined products |
| CN109136539B (en) * | 2018-07-05 | 2020-06-23 | 沈阳化工大学 | Integrated process of fluidized bed two-stage gasification and flash light burning magnesite |
Family Cites Families (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NL74181C (en) * | 1945-03-02 | 1900-01-01 | ||
| BE508537A (en) * | 1951-02-08 | |||
| US2772950A (en) * | 1952-04-01 | 1956-12-04 | Columbia Southern Chem Corp | Calcination of barium carbonate |
| FR2132956A5 (en) * | 1971-04-02 | 1972-11-24 | Kunii Daizo | Lime slaking - in fluid bed reactor |
| US3743697A (en) * | 1971-10-28 | 1973-07-03 | Paraho Corp | Process of calcination |
| US3961903A (en) * | 1971-12-20 | 1976-06-08 | Nichols Engineering & Research Corporation | Apparatus for reclaiming limestone mud |
| DE2407506C3 (en) * | 1974-02-16 | 1978-05-24 | Hoechst Ag, 6000 Frankfurt | Method and device for calcining hydrated lime moldings |
| DE2657135C2 (en) * | 1976-12-16 | 1986-11-13 | Fritz Dr.-Ing. 8192 Geretsried Schoppe | Device for the continuous production of active calcium oxide in powder form by calcining waste lime containing organic substances from the sugar industry |
| FR2291161A1 (en) * | 1974-06-06 | 1976-06-11 | Schoppe Fritz | Lime recovery from (sugar ind) waste slurry - by heat treatment in suspension in rising hot air stream |
| FR2311764A1 (en) * | 1975-05-23 | 1976-12-17 | Rhone Poulenc Ind | METHOD AND APPARATUS FOR THERMAL TRANSFORMATION OF GYPSUM |
| DE2705710C3 (en) * | 1977-02-11 | 1980-06-04 | Kloeckner-Humboldt-Deutz Ag, 5000 Koeln | Countercurrent burning process for the production of quicklime and shaft furnace for carrying out the process |
| DE2812454A1 (en) * | 1978-03-22 | 1979-10-04 | Raoul Borner | Burner for crushed raw powder - has closed furnace chamber through which gas current flows under negative pressure |
| JPS5551784A (en) * | 1978-10-09 | 1980-04-15 | Denpatsu Fly Ash | Method and apparatus for manufacturing potassium silicate fertilizer |
-
1980
- 1980-05-20 CH CH390280A patent/CH645083A5/en not_active IP Right Cessation
-
1981
- 1981-04-25 DE DE19813116572 patent/DE3116572A1/en not_active Ceased
- 1981-04-29 ZA ZA00812839A patent/ZA812839B/en unknown
- 1981-05-04 CA CA000376832A patent/CA1162402A/en not_active Expired
- 1981-05-13 BR BR8102986A patent/BR8102986A/en unknown
- 1981-05-18 IT IT2177181A patent/IT1135838B/en active
- 1981-05-18 LU LU83373A patent/LU83373A1/en unknown
- 1981-05-19 BE BE0/204829A patent/BE888860A/en unknown
- 1981-05-19 AT AT223081A patent/AT383106B/en not_active IP Right Cessation
- 1981-05-19 FR FR8109907A patent/FR2482946A1/en active Granted
- 1981-05-19 PL PL23123881A patent/PL231238A1/xx unknown
- 1981-05-19 AU AU70824/81A patent/AU546179B2/en not_active Ceased
- 1981-05-19 ES ES502303A patent/ES502303A0/en active Granted
- 1981-05-19 GB GB8115338A patent/GB2076308B/en not_active Expired
- 1981-05-19 DK DK219581A patent/DK219581A/en not_active Application Discontinuation
- 1981-05-19 NL NL8102461A patent/NL8102461A/en not_active Application Discontinuation
- 1981-05-20 JP JP7504381A patent/JPS5716714A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| ZA812839B (en) | 1982-04-28 |
| AU7082481A (en) | 1981-11-26 |
| BE888860A (en) | 1981-09-16 |
| IT8121771A0 (en) | 1981-05-18 |
| BR8102986A (en) | 1982-02-02 |
| GB2076308A (en) | 1981-12-02 |
| FR2482946A1 (en) | 1981-11-27 |
| LU83373A1 (en) | 1981-09-11 |
| PL231238A1 (en) | 1982-01-04 |
| ES8206385A1 (en) | 1982-08-16 |
| DE3116572A1 (en) | 1982-06-03 |
| AT383106B (en) | 1987-05-25 |
| DK219581A (en) | 1981-11-21 |
| CH645083A5 (en) | 1984-09-14 |
| ATA223081A (en) | 1986-10-15 |
| ES502303A0 (en) | 1982-08-16 |
| NL8102461A (en) | 1981-12-16 |
| GB2076308B (en) | 1984-06-20 |
| AU546179B2 (en) | 1985-08-22 |
| IT1135838B (en) | 1986-08-27 |
| FR2482946B1 (en) | 1984-11-09 |
| JPS5716714A (en) | 1982-01-28 |
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