US20110033351A1 - System and method for calcining gypsum - Google Patents
System and method for calcining gypsum Download PDFInfo
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- US20110033351A1 US20110033351A1 US12/537,617 US53761709A US2011033351A1 US 20110033351 A1 US20110033351 A1 US 20110033351A1 US 53761709 A US53761709 A US 53761709A US 2011033351 A1 US2011033351 A1 US 2011033351A1
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- gypsum
- mill
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- air heater
- dried
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- 239000010440 gypsum Substances 0.000 title claims abstract description 160
- 229910052602 gypsum Inorganic materials 0.000 title claims abstract description 160
- 238000001354 calcination Methods 0.000 title claims abstract description 35
- 238000000034 method Methods 0.000 title claims description 20
- 230000007246 mechanism Effects 0.000 claims abstract description 15
- 238000000227 grinding Methods 0.000 claims abstract description 14
- 238000001035 drying Methods 0.000 claims abstract description 11
- 239000000428 dust Substances 0.000 claims description 20
- 239000007789 gas Substances 0.000 description 76
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 description 8
- 239000006227 byproduct Substances 0.000 description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 6
- 239000002245 particle Substances 0.000 description 5
- 230000003134 recirculating effect Effects 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 3
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 239000002002 slurry Substances 0.000 description 2
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- 235000019738 Limestone Nutrition 0.000 description 1
- 229910019142 PO4 Inorganic materials 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 1
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 1
- KGBXLFKZBHKPEV-UHFFFAOYSA-N boric acid Chemical compound OB(O)O KGBXLFKZBHKPEV-UHFFFAOYSA-N 0.000 description 1
- 239000004327 boric acid Substances 0.000 description 1
- PASHVRUKOFIRIK-UHFFFAOYSA-L calcium sulfate dihydrate Chemical compound O.O.[Ca+2].[O-]S([O-])(=O)=O PASHVRUKOFIRIK-UHFFFAOYSA-L 0.000 description 1
- ZOMBKNNSYQHRCA-UHFFFAOYSA-J calcium sulfate hemihydrate Chemical compound O.[Ca+2].[Ca+2].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O ZOMBKNNSYQHRCA-UHFFFAOYSA-J 0.000 description 1
- 238000001311 chemical methods and process Methods 0.000 description 1
- 238000006477 desulfuration reaction Methods 0.000 description 1
- 230000023556 desulfurization Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000003546 flue gas Substances 0.000 description 1
- 239000010436 fluorite Substances 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
- 239000006028 limestone Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000003801 milling Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000003472 neutralizing effect Effects 0.000 description 1
- 239000010452 phosphate Substances 0.000 description 1
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 1
- 239000000049 pigment Substances 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 239000011435 rock Substances 0.000 description 1
- 238000005201 scrubbing Methods 0.000 description 1
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 description 1
- 239000002918 waste heat Substances 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Images
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
- C04B11/00—Calcium sulfate cements
- C04B11/02—Methods and apparatus for dehydrating gypsum
- C04B11/028—Devices therefor characterised by the type of calcining devices used therefor or by the type of hemihydrate obtained
- C04B11/0286—Suspension heaters for flash calcining, e.g. cyclones
-
- 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
- F27B15/00—Fluidised-bed furnaces; Other furnaces using or treating finely-divided materials in dispersion
- F27B15/006—Equipment for treating dispersed material falling under gravity with ascending gases
Definitions
- the disclosed subject matter relates to a system and method for calcining gypsum. More specifically, the disclosed subject matter relates to a system and method for calcining natural gypsum, synthetic gypsum, or a combination thereof.
- Gypsum can be either natural gypsum that is mines or synthetically produced gypsum. Natural gypsum is hard and resembles rocks. It must be crushed before use. Synthetic gypsum is typically created from powdered limestone that combines with SO 2 and SO 3 gasses in the scrubbers of power plants.
- Calcined gypsum (also known as stucco) has a wide variety of uses. Calcined gypsum is most commonly known for its use in drywall (also known as wallboard or gypsum board), manufactured commercially by processes that provide an aqueous slurry of calcined gypsum and other ingredients to be deposited between two sheets of cover paper to form a core between those sheets.
- Calcination refers to the conversion of calcium sulfate dehydrate to calcium sulfate hemihydrates.
- the process is typically conducted by exposing gypsum to high temperatures for a short period of time in a calciner.
- Roller mills can be used for grinding but cannot be used for calcining. They can be used for drying material. These are preferred to be used for natural gypsum. Roller mill is often used for grinding natural gypsum and a kettle for calcining natural gypsum.
- impact mills There are also impact mills. These can be used for both grinding and for calcining. However, using impact mills for natural gypsum require significantly more energy to run than roller mills. Therefore, the resulting product from processing natural gypsum using impact mills becomes more costly.
- Another drawback is that current technology does not provide the flexibility to process only natural gypsum, only synthetic gypsum or a combination thereof.
- a system for calcining natural gypsum, synthetic gypsum or a combination thereof comprising: a mill for grinding and drying natural gypsum, synthetic gypsum or a combination thereof, to produce dried gypsum; a flash calciner for calcining the dried gypsum to produce an exhaust gas and calcined gypsum; and a mechanism for transporting at least a portion of the exhaust gas produced by the flash calciner to an air heater that supplies hot gas to the flash calciner.
- a process for calcining natural gypsum, synthetic gypsum or a combination thereof comprising: supplying natural gypsum, synthetic gypsum or a combination thereof to a mill; grinding and drying the natural gypsum, synthetic gypsum or a combination thereof in the mill to form dried gypsum and a first exhaust gas; supplying the dried gypsum to a flash calciner; calcining the dried gypsum in the flash calciner, thereby producing a second exhaust gas and calcined gypsum; and transporting at least a portion of the second exhaust gas to an air heater that provides hot gas to the flash calciner.
- a system for calcining gypsum comprising: a mill for grinding and drying gypsum, thereby producing dried gypsum and a first exhaust gas, wherein the mill is selected from a roller mill or a hammer impact mill, and further wherein the gypsum is selected from natural gypsum, synthetic gypsum or a combination thereof, a flash calciner for calcining the dried gypsum, thereby producing calcined gypsum and a second exhaust gas; and a mechanism for transporting the second exhaust gas produced by the flash calciner to a first air heater coupled to the flash calciner.
- FIG. 1 is a diagram depicting an example of one embodiment of a system for calcining gypsum
- FIG. 2 is a diagram depicting an example of another embodiment of a system for calcining gypsum.
- FIG. 3 is a diagram depicting an example of another embodiment of a system for calcining gypsum.
- Synthetic gypsum also known as “by-product gypsum”, is typically produced as a by-product in various chemical processes.
- flue gas desulfurization (FGD) gypsum is a by-product of stack gas scrubbing processes.
- Other types of synthetic gypsum may also be created by various other processes.
- titanogypsum is produced by neutralizing waste sulfuric acid from the sulfate process used to manufacture titanium oxide pigment; phosphogypsum is a by-product produced when phosphate ore is acidulated to extract phosphoric acid; fluorogypsum is a by-product of the fluorspar acidulation reaction used to produce hydrofluoric acid; citrogypsum is a by-product of a process for producing citric acid; and borogypsum is a by-product of a process for producing boric acid.
- Synthetic gypsum typically includes more free water (water not bound to calcium sulfate) than natural gypsum.
- Natural gypsum typically includes about 1%-3% free water (unless otherwise indicated, percentages herein indicate percent by weight), compared to synthetic gypsum which is typically mechanically de-watered to a slurry containing about 10%-15% free water.
- FIG. 1 illustrates a system for calcining gypsum, shown generally at 100 .
- gypsum 112 is supplied to a mill 114 .
- the gypsum 112 can be natural gypsum, synthetic gypsum, or a combination thereof.
- the gypsum 112 is supplied to the mill 114 by any process transport means including, for example, pipes, conveyors, ducts, other conduits, and the like.
- the gypsum 112 is ground and dried in the mill 114 to produced dried gypsum 116 .
- the dried gypsum 116 is present in an exhaust gas 123 for transport to other sections of system 100 .
- the gypsum 112 is supplied to the mill 114 at a constant rate or, alternatively, is supplied to the mill 114 on an “as-needed” basis.
- the supply of the gypsum 112 to the mill 114 may be controlled by a control valve, a transducer providing, for example, temperature, pressure or electrical control, microprocessor based logic, or the like.
- the mill 114 may be any apparatus that grinds and dries the gypsum 112 .
- suitable mills include, but are not limited to, for example, pendulum type roller mills, bowl mill pulverizers, and impact mills, including, for example an impact hammer mill, such as a Raymond® Imp Mill available from Alstom Power Inc., Air Preheater Company (Wellsville, N.Y., USA).
- FIGS. 1 and 3 illustrate a roller mill 114 , 314
- FIG. 2 illustrates an impact hammer mill 214 , and more specifically, an imp mill such as, for example, the aforementioned Raymond® Imp Mill.
- gypsum 112 is supplied to the imp mill 114 via a feeder 213 .
- the feeder 213 provides a constant supply of the gypsum 112 to the imp mill 114 .
- the imp mill 114 is coupled to a particle classifier 215 , which separates dried gypsum 116 based on the size of particles present therein. For example, particles over a predetermined size (e.g., oversized particles) 217 are provided back to the feeder 213 to be supplied to the imp mill 114 for further processing (e.g., grinding and drying).
- a predetermined size e.g., oversized particles
- the dried gypsum 116 and exhaust gas 123 are supplied to a flash calciner 118 .
- the dried gypsum 116 passes through a dust collector 120 , a feed bin 122 and a dispersing feeder 124 , before it is supplied to the flash calciner 118 .
- the dust collector 120 facilitates the removal of the dried gypsum 116 from the exhaust gas 123 while the feed bin 122 stores the dried gypsum 116 until it is dispensed to the flash calciner 118 via the dispersing feeder 124 .
- a portion of the exhaust gas 123 is vented to the atmosphere, while another portion of the exhaust gas 123 is recirculated to mill 114 .
- the dried gypsum 116 may be transported and supplied to the dust collector 120 , the feed bin 122 , the dispersing feeder 124 and the flash calciner 118 via, for example, pipes, conveyors, ducts, other conduits, and the like. As noted above, in one example, the dried gypsum 116 is transported with the exhaust gas 123 . It is noted that in one example, the dust collector 120 may be replaced with a cyclone and a relatively smaller size dust collector (not shown in FIG. 1 ).
- Calcining e.g., the conversion of calcium sulfate dehydrate to calcium sulfate hemihydrate, of the dried gypsum 116 occurs in the flash calciner 118 .
- the flash calciner 118 receives a stream of hot gas 126 a from an air heater 126 .
- the stream of hot gas 126 a has a temperature in a range of, for example, between about one thousand degrees Fahrenheit (1000° F.) and fourteen hundred degrees Fahrenheit (1400° F.).
- Calcining of the dried gypsum 116 facilitates the removal of bound moisture present in the dried gypsum 116 .
- calcining of the dried gypsum 116 produces calcined gypsum 128 as well as an exhaust gas 130 , which travel together to a calciner dust collector 132 .
- the exhaust gas 130 has a temperature in a range of, for example, between about three hundred degrees Fahrenheit (300° F.) and three hundred fifty degrees Fahrenheit (350° F.).
- the calciner dust collector 132 removes dust particles and calcined gypsum 128 from the exhaust gas 130 and releases the exhaust gas 130 (as described below) to an environment such as, for example, the atmosphere. In one embodiment, the calciner dust collector 132 releases calcined gypsum 128 (e.g., stucco) to another section of system 100 . In one example, the calciner dust collector 132 may be replaced with a cyclone and a relatively smaller size dust collector (not shown in FIG. 1 ). The calcined gypsum 128 proceeds to other sections of system 100 (not shown) or may be stored for transport and/or future use.
- calcined gypsum 128 proceeds to other sections of system 100 (not shown) or may be stored for transport and/or future use.
- the exhaust gas 130 is transported to the air heater 126 by a mechanism 134 .
- the mechanism 134 may be any apparatus that facilitates the diversion and transportation of at least a portion of the exhaust gas 130 to the air heater 126 . Examples of the mechanism 134 include, but are not limited to, for example, a teed duct, and the like. In one embodiment, the mechanism 134 may be controlled by microprocessor based logic or another type of controller (not shown).
- the exhaust gas 130 travels through a calciner vent fan 136 and a recirculating damper 138 .
- the exhaust gas 130 may be supplied directly to the air heater 126 without passing through the calciner vent fan 136 and the recirculating damper 138 .
- the recirculating damper 138 may be controlled by microprocessor based logic or another type of controller (not shown). It is also contemplated that the exhaust gas 130 may pass through other devices prior to reaching the air heater 126 .
- the air heater 126 utilizes the exhaust gas 130 to produce the stream of hot gas 126 a.
- the hot gas 126 a is supplied to the flash calciner 118 .
- the hot gas 126 a is supplied to both the flash calciner 118 and the mill 114 .
- the hot gas 126 a is supplied to either the flash calciner 118 , the mill 114 , or both, through any mechanism able to facilitate the transfer of the hot gas.
- the hot gas 126 a may be supplied by, for example, pipes, ducts, conduits, pumps, valves, and the like.
- the exhaust gas 130 is combined with an air stream 140 , which is provided by the atmosphere.
- the air stream 140 may be heated in an air preheater 142 prior to entering the air heater 126 .
- the air stream 140 is not heated prior to entering the air heater 126 .
- the air heater 126 utilizes only the exhaust gas 130 to generate the stream of hot gas 126 a.
- gypsum 112 is supplied to mill 114 .
- mill 114 may be any apparatus that grinds and dries the gypsum 112 to produce dried gypsum 116 .
- dried gypsum 116 is produced with an exhaust gas 123 .
- Dried gypsum 116 and exhaust gas 123 are sent to a mill cyclone 321 , which collects and separates the dried gypsum 116 from the exhaust gas 123 .
- the separated dried gypsum 116 proceeds to feed bin 122 , while a portion of exhaust gas 123 having some dried gypsum 116 therein, proceeds to dust collector 120 .
- Dust collector 120 further separates any remaining dried gypsum 116 from the exhaust gas 123 .
- the dried gypsum 116 separated in the dust collector 120 is sent to the feed bin 122 . It is contemplated that system 300 may not include mill cyclone 321 , and accordingly, dried gypsum 116 would proceed straight to dust collector 120 .
- Air heater 325 utilizes exhaust gas 123 to produce a stream of hot gas 325 a that is supplied to the mill 114 .
- Hot gas 325 a may be supplied to the mill 114 by any mechanism able to facilitate the transfer of hot gas 325 a to the mill. Examples include, but are not limited to conduits, pumps, valves, ducts, pipes, and the like.
- Feed bin 122 stores the dried gypsum 116 until it is dispensed to the flash calciner 118 via the dispersing feeder 124 .
- Calcining of the dried gypsum 116 produces calcined gypsum 128 as well as an exhaust gas 130 , which travel together to a calciner cyclone 333 .
- Calciner cyclone 333 removes calcined gypsum 128 and releases it to another section of system 300 .
- the exhaust gas 130 travels through a calciner vent fan 136 and a recirculating damper 138 .
- Air heater 126 utilizes the exhaust gas 130 to produce the stream of hot gas 126 a, which is provided to the flash calciner 118 .
- the exhaust gas 130 is combined with an air stream 140 , which is provided by the atmosphere.
- the air stream 140 may be heated in an air preheater 142 prior to entering air heater 126 .
- air stream 140 is not heated prior to entering the air heater 126 .
- systems 100 , 200 and 300 process the gypsum 112 by supplying the gypsum to the mill 114 .
- the gypsum 112 supplied to the mill 114 is natural, synthetic or a combination thereof.
- the gypsum 112 is supplied to the mill 114 by any mechanism capable of transporting the gypsum to the mills, including, but not limited to, for example, pipes, ducts, valves, conduits, conveyors, and the like.
- the gypsum 112 is ground and dried in the mill 114 to form the dried gypsum 116 and exhaust gas 123 . It should be appreciated that grinding of gypsum in a mill may be performed by, for example, crushing or grinding mechanisms, such as hammers, while drying gypsum in the mill 114 may be performed by contacting the gypsum with a stream of air or hot gas.
- exhaust gas 123 is transported to the air heater 325 , which produces hot gas 325 a that is transported to mill 114 .
- the dried gypsum 116 is then supplied to the flash calciner 118 where it is calcined. Calcining of the dried gypsum 116 produces the calcined gypsum 128 as well as the exhaust gas 130 .
- At least a portion of the exhaust gas 130 is transported to the air heater 126 via ducts, pipes, conduits, and the like.
- the exhaust gas 130 is utilized in the air heater 126 to produce hot gas streams 126 a.
- the hot gas stream 126 a is supplied to the flash calciners 118 .
- the hot gas stream 126 a is supplied to the mill 114 .
- at least a portion of the hot gas stream 126 a is supplied to the flash calciner 118 and another portion of the hot gas stream 126 a is supplied to the mill 114 .
- the hot gas stream 126 a may be supplied to the flash calciner 118 and/or the mill 114 via any mechanism adapted to do so, including, but not limited to, for example, pipes, ducts, conduits, and the like.
- Fans and dampers may be utilized in supplying the flash calciner 118 and/or the mill 114 with the hot gas stream 126 a.
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Abstract
Description
- 1. Field of the Invention
- The disclosed subject matter relates to a system and method for calcining gypsum. More specifically, the disclosed subject matter relates to a system and method for calcining natural gypsum, synthetic gypsum, or a combination thereof.
- 2. Description of Related Art
- Gypsum can be either natural gypsum that is mines or synthetically produced gypsum. Natural gypsum is hard and resembles rocks. It must be crushed before use. Synthetic gypsum is typically created from powdered limestone that combines with SO2 and SO3 gasses in the scrubbers of power plants.
- Calcined gypsum (also known as stucco) has a wide variety of uses. Calcined gypsum is most commonly known for its use in drywall (also known as wallboard or gypsum board), manufactured commercially by processes that provide an aqueous slurry of calcined gypsum and other ingredients to be deposited between two sheets of cover paper to form a core between those sheets.
- Calcination (or “calcining”) refers to the conversion of calcium sulfate dehydrate to calcium sulfate hemihydrates. The process is typically conducted by exposing gypsum to high temperatures for a short period of time in a calciner.
- Roller mills can be used for grinding but cannot be used for calcining. They can be used for drying material. These are preferred to be used for natural gypsum. Roller mill is often used for grinding natural gypsum and a kettle for calcining natural gypsum.
- There are also impact mills. These can be used for both grinding and for calcining. However, using impact mills for natural gypsum require significantly more energy to run than roller mills. Therefore, the resulting product from processing natural gypsum using impact mills becomes more costly.
- However, for synthetic gypsum, there is not much of a difference in energy required to operate roller mills versus impact mills. This is due to the fact that synthetic gypsum is typically in granular form and does not require a great deal of milling.
- Since synthetic gypsum has higher water content than natural gypsum, a cage mill is often used for drying first. An impact mill is then used for grinding and calcining in a single step. Prior efforts for calcining synthetic gypsum in a single step have resulted in lack of calcining uniformity, which reduces the quality of the calcined gypsum.
- Another drawback is that current technology does not provide the flexibility to process only natural gypsum, only synthetic gypsum or a combination thereof.
- According to aspects illustrated herein, there is provided a system for calcining natural gypsum, synthetic gypsum or a combination thereof, the system comprising: a mill for grinding and drying natural gypsum, synthetic gypsum or a combination thereof, to produce dried gypsum; a flash calciner for calcining the dried gypsum to produce an exhaust gas and calcined gypsum; and a mechanism for transporting at least a portion of the exhaust gas produced by the flash calciner to an air heater that supplies hot gas to the flash calciner.
- According to another aspect illustrated herein, there is provided a process for calcining natural gypsum, synthetic gypsum or a combination thereof, the process comprising: supplying natural gypsum, synthetic gypsum or a combination thereof to a mill; grinding and drying the natural gypsum, synthetic gypsum or a combination thereof in the mill to form dried gypsum and a first exhaust gas; supplying the dried gypsum to a flash calciner; calcining the dried gypsum in the flash calciner, thereby producing a second exhaust gas and calcined gypsum; and transporting at least a portion of the second exhaust gas to an air heater that provides hot gas to the flash calciner.
- According to another aspect illustrated herein, there is provided a system for calcining gypsum, the system comprising: a mill for grinding and drying gypsum, thereby producing dried gypsum and a first exhaust gas, wherein the mill is selected from a roller mill or a hammer impact mill, and further wherein the gypsum is selected from natural gypsum, synthetic gypsum or a combination thereof, a flash calciner for calcining the dried gypsum, thereby producing calcined gypsum and a second exhaust gas; and a mechanism for transporting the second exhaust gas produced by the flash calciner to a first air heater coupled to the flash calciner.
- The above described and other features are exemplified by the following figures and detailed description.
- Referring now to the figures, which are exemplary embodiments, and wherein the like elements are numbered alike:
-
FIG. 1 is a diagram depicting an example of one embodiment of a system for calcining gypsum; -
FIG. 2 is a diagram depicting an example of another embodiment of a system for calcining gypsum; and -
FIG. 3 is a diagram depicting an example of another embodiment of a system for calcining gypsum. - Synthetic gypsum, also known as “by-product gypsum”, is typically produced as a by-product in various chemical processes. As stated above, flue gas desulfurization (FGD) gypsum is a by-product of stack gas scrubbing processes. Other types of synthetic gypsum may also be created by various other processes. For example, titanogypsum is produced by neutralizing waste sulfuric acid from the sulfate process used to manufacture titanium oxide pigment; phosphogypsum is a by-product produced when phosphate ore is acidulated to extract phosphoric acid; fluorogypsum is a by-product of the fluorspar acidulation reaction used to produce hydrofluoric acid; citrogypsum is a by-product of a process for producing citric acid; and borogypsum is a by-product of a process for producing boric acid.
- Synthetic gypsum typically includes more free water (water not bound to calcium sulfate) than natural gypsum. Natural gypsum typically includes about 1%-3% free water (unless otherwise indicated, percentages herein indicate percent by weight), compared to synthetic gypsum which is typically mechanically de-watered to a slurry containing about 10%-15% free water.
- What is needed is a system that can make use of use natural gypsum that is mined. As more power plants are coming on-line, there will be a greater supply of synthetic gypsum. The system will begin to be used in a mixture with natural gypsum. And possibly, there may be a time when only synthetic gypsum is used. Therefore, there is a need for a system that can produce calcined gypsum of a consistently high quality, regardless of the relative mixture of natural to synthetic gypsum, and regardless of the water content of the gypsum being used.
- It is also important that the system makes efficient use of energy, including recycling of waste heat. This allows for a competitively priced product.
-
FIG. 1 illustrates a system for calcining gypsum, shown generally at 100. In one example of thesystem 100,gypsum 112 is supplied to amill 114. Thegypsum 112 can be natural gypsum, synthetic gypsum, or a combination thereof. - As illustrated in
FIG. 1 , thegypsum 112 is supplied to themill 114 by any process transport means including, for example, pipes, conveyors, ducts, other conduits, and the like. Thegypsum 112 is ground and dried in themill 114 to produced driedgypsum 116. In one embodiment, thedried gypsum 116 is present in anexhaust gas 123 for transport to other sections ofsystem 100. - In one embodiment, the
gypsum 112 is supplied to themill 114 at a constant rate or, alternatively, is supplied to themill 114 on an “as-needed” basis. In one embodiment, the supply of thegypsum 112 to themill 114 may be controlled by a control valve, a transducer providing, for example, temperature, pressure or electrical control, microprocessor based logic, or the like. - It should be appreciated that the
mill 114 may be any apparatus that grinds and dries thegypsum 112. Some examples of suitable mills include, but are not limited to, for example, pendulum type roller mills, bowl mill pulverizers, and impact mills, including, for example an impact hammer mill, such as a Raymond® Imp Mill available from Alstom Power Inc., Air Preheater Company (Wellsville, N.Y., USA).FIGS. 1 and 3 illustrate aroller mill 114, 314, whileFIG. 2 illustrates an impact hammer mill 214, and more specifically, an imp mill such as, for example, the aforementioned Raymond® Imp Mill. - Referring to
FIG. 2 , wherein like numbers equal like parts as referred to inFIG. 1 ,gypsum 112 is supplied to theimp mill 114 via afeeder 213. Thefeeder 213 provides a constant supply of thegypsum 112 to theimp mill 114. - In one example, the
imp mill 114 is coupled to aparticle classifier 215, which separates driedgypsum 116 based on the size of particles present therein. For example, particles over a predetermined size (e.g., oversized particles) 217 are provided back to thefeeder 213 to be supplied to theimp mill 114 for further processing (e.g., grinding and drying). - Referring back to
FIG. 1 , in one embodiment, the driedgypsum 116 andexhaust gas 123 are supplied to aflash calciner 118. In one example, as shown inFIG. 1 , the driedgypsum 116 passes through adust collector 120, afeed bin 122 and a dispersingfeeder 124, before it is supplied to theflash calciner 118. Thedust collector 120 facilitates the removal of the driedgypsum 116 from theexhaust gas 123 while thefeed bin 122 stores the driedgypsum 116 until it is dispensed to theflash calciner 118 via the dispersingfeeder 124. A portion of theexhaust gas 123 is vented to the atmosphere, while another portion of theexhaust gas 123 is recirculated tomill 114. - The dried
gypsum 116 may be transported and supplied to thedust collector 120, thefeed bin 122, the dispersingfeeder 124 and theflash calciner 118 via, for example, pipes, conveyors, ducts, other conduits, and the like. As noted above, in one example, the driedgypsum 116 is transported with theexhaust gas 123. It is noted that in one example, thedust collector 120 may be replaced with a cyclone and a relatively smaller size dust collector (not shown inFIG. 1 ). - Calcining, e.g., the conversion of calcium sulfate dehydrate to calcium sulfate hemihydrate, of the dried
gypsum 116 occurs in theflash calciner 118. In one embodiment, to facilitate calcining, theflash calciner 118 receives a stream ofhot gas 126 a from anair heater 126. In one embodiment, the stream ofhot gas 126 a has a temperature in a range of, for example, between about one thousand degrees Fahrenheit (1000° F.) and fourteen hundred degrees Fahrenheit (1400° F.). Calcining of the driedgypsum 116 facilitates the removal of bound moisture present in the driedgypsum 116. - In one embodiment, calcining of the dried
gypsum 116 produces calcinedgypsum 128 as well as anexhaust gas 130, which travel together to acalciner dust collector 132. In one embodiment, theexhaust gas 130 has a temperature in a range of, for example, between about three hundred degrees Fahrenheit (300° F.) and three hundred fifty degrees Fahrenheit (350° F.). - The
calciner dust collector 132 removes dust particles and calcinedgypsum 128 from theexhaust gas 130 and releases the exhaust gas 130 (as described below) to an environment such as, for example, the atmosphere. In one embodiment, thecalciner dust collector 132 releases calcined gypsum 128 (e.g., stucco) to another section ofsystem 100. In one example, thecalciner dust collector 132 may be replaced with a cyclone and a relatively smaller size dust collector (not shown inFIG. 1 ). Thecalcined gypsum 128 proceeds to other sections of system 100 (not shown) or may be stored for transport and/or future use. - As shown in
FIG. 1 , in one embodiment, after passing through thecalciner dust collector 132, at least a portion ofexhaust gas 130 is transported to theair heater 126, while another portion of the exhaust gas is vented to the atmosphere. In one example, as shown inFIG. 1 , theexhaust gas 130 is transported to theair heater 126 by amechanism 134. In one embodiment, themechanism 134 may be any apparatus that facilitates the diversion and transportation of at least a portion of theexhaust gas 130 to theair heater 126. Examples of themechanism 134 include, but are not limited to, for example, a teed duct, and the like. In one embodiment, themechanism 134 may be controlled by microprocessor based logic or another type of controller (not shown). - In one embodiment, prior to being transported to the
air heater 126, theexhaust gas 130 travels through acalciner vent fan 136 and arecirculating damper 138. However, it is contemplated that theexhaust gas 130 may be supplied directly to theair heater 126 without passing through thecalciner vent fan 136 and therecirculating damper 138. In one embodiment, therecirculating damper 138 may be controlled by microprocessor based logic or another type of controller (not shown). It is also contemplated that theexhaust gas 130 may pass through other devices prior to reaching theair heater 126. - The
air heater 126 utilizes theexhaust gas 130 to produce the stream ofhot gas 126 a. In one embodiment, thehot gas 126 a is supplied to theflash calciner 118. In another embodiment, and as shown inFIG. 1 , thehot gas 126 a is supplied to both theflash calciner 118 and themill 114. Thehot gas 126 a is supplied to either theflash calciner 118, themill 114, or both, through any mechanism able to facilitate the transfer of the hot gas. Thehot gas 126 a may be supplied by, for example, pipes, ducts, conduits, pumps, valves, and the like. - It should be appreciated that utilization of the
exhaust gas 130 to produce the stream ofhot gas 126 a reduces the amount of energy needed to produce the stream of hot gas for theflash calciner 118 since theexhaust gas 130 usually has a temperature in a range of, for example, between about three hundred degrees Fahrenheit (300° F.) and three hundred fifty degrees Fahrenheit (350° F.). - In one example, as shown in
FIG. 1 , in theair heater 126, theexhaust gas 130 is combined with anair stream 140, which is provided by the atmosphere. As shown inFIG. 1 , theair stream 140 may be heated in anair preheater 142 prior to entering theair heater 126. However, it is contemplated that theair stream 140 is not heated prior to entering theair heater 126. While not shown, it is contemplated that in another example theair heater 126 utilizes only theexhaust gas 130 to generate the stream ofhot gas 126 a. - In another embodiment, as shown in
FIG. 3 , wherein like numbers equal like parts as referred to inFIG. 1 ,gypsum 112 is supplied tomill 114. As discussed above,mill 114 may be any apparatus that grinds and dries thegypsum 112 to produce driedgypsum 116. In one embodiment, driedgypsum 116 is produced with anexhaust gas 123. - Dried
gypsum 116 andexhaust gas 123 are sent to amill cyclone 321, which collects and separates the driedgypsum 116 from theexhaust gas 123. The separated driedgypsum 116 proceeds to feedbin 122, while a portion ofexhaust gas 123 having some driedgypsum 116 therein, proceeds todust collector 120.Dust collector 120 further separates any remaining driedgypsum 116 from theexhaust gas 123. The driedgypsum 116 separated in thedust collector 120 is sent to thefeed bin 122. It is contemplated thatsystem 300 may not includemill cyclone 321, and accordingly, driedgypsum 116 would proceed straight todust collector 120. - Another portion of
exhaust gas 123 and driedgypsum 116 proceed frommill cyclone 321 toair heater 325.Air heater 325 utilizesexhaust gas 123 to produce a stream ofhot gas 325 a that is supplied to themill 114.Hot gas 325 a may be supplied to themill 114 by any mechanism able to facilitate the transfer ofhot gas 325 a to the mill. Examples include, but are not limited to conduits, pumps, valves, ducts, pipes, and the like. -
Feed bin 122 stores the driedgypsum 116 until it is dispensed to theflash calciner 118 via the dispersingfeeder 124. Calcining of the driedgypsum 116 produces calcinedgypsum 128 as well as anexhaust gas 130, which travel together to acalciner cyclone 333.Calciner cyclone 333 removes calcinedgypsum 128 and releases it to another section ofsystem 300. - As shown in
FIG. 3 , after proceeding throughcalciner cyclone 333, at least a portion ofexhaust gas 130 is transported toair heater 126, while another portion of the exhaust gas is brought todust collector 331. Thedust collector 331 removes any remaining particulates present in theexhaust gas 130 prior to its release to the atmosphere. - As shown in
FIG. 3 , prior to being transported to air heater 326, theexhaust gas 130 travels through acalciner vent fan 136 and arecirculating damper 138. -
Air heater 126 utilizes theexhaust gas 130 to produce the stream ofhot gas 126 a, which is provided to theflash calciner 118. In one example, as shown inFIG. 3 , in theair heater 126, theexhaust gas 130 is combined with anair stream 140, which is provided by the atmosphere. As shown inFIG. 3 , theair stream 140 may be heated in anair preheater 142 prior to enteringair heater 126. However, it is contemplated thatair stream 140 is not heated prior to entering theair heater 126. - In use,
systems gypsum 112 by supplying the gypsum to themill 114. It should be appreciated that thegypsum 112 supplied to themill 114 is natural, synthetic or a combination thereof. In one embodiment, thegypsum 112 is supplied to themill 114 by any mechanism capable of transporting the gypsum to the mills, including, but not limited to, for example, pipes, ducts, valves, conduits, conveyors, and the like. - The
gypsum 112 is ground and dried in themill 114 to form the driedgypsum 116 andexhaust gas 123. It should be appreciated that grinding of gypsum in a mill may be performed by, for example, crushing or grinding mechanisms, such as hammers, while drying gypsum in themill 114 may be performed by contacting the gypsum with a stream of air or hot gas. - In one embodiment,
exhaust gas 123 is transported to theair heater 325, which produceshot gas 325 a that is transported tomill 114. The driedgypsum 116 is then supplied to theflash calciner 118 where it is calcined. Calcining of the driedgypsum 116 produces thecalcined gypsum 128 as well as theexhaust gas 130. At least a portion of theexhaust gas 130 is transported to theair heater 126 via ducts, pipes, conduits, and the like. - The
exhaust gas 130 is utilized in theair heater 126 to producehot gas streams 126 a. In one example, thehot gas stream 126 a is supplied to theflash calciners 118. In another example, thehot gas stream 126 a is supplied to themill 114. In another example, at least a portion of thehot gas stream 126 a is supplied to theflash calciner 118 and another portion of thehot gas stream 126 a is supplied to themill 114. Thehot gas stream 126 a may be supplied to theflash calciner 118 and/or themill 114 via any mechanism adapted to do so, including, but not limited to, for example, pipes, ducts, conduits, and the like. Fans and dampers may be utilized in supplying theflash calciner 118 and/or themill 114 with thehot gas stream 126 a. - Unless otherwise specified, all ranges disclosed herein are inclusive and combinable at the end points and all intermediate points therein. The terms “first,” “second,” and the like, herein do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. The terms “a” and “an” herein do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item. All numerals modified by “about” are inclusive of the precise numeric value unless otherwise specified.
- While the invention has been described with reference to various exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.
Claims (18)
Priority Applications (6)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US12/537,617 US7897134B1 (en) | 2009-08-07 | 2009-08-07 | System and method for calcining gypsum |
PCT/US2010/039564 WO2011016912A1 (en) | 2009-08-07 | 2010-06-23 | System and method for calcining gypsum |
BR112012002703-4A BR112012002703B1 (en) | 2009-08-07 | 2010-06-23 | system and process for calcining natural plaster, synthetic plaster or a combination thereof |
ARP100102728A AR077602A1 (en) | 2009-08-07 | 2010-07-28 | SYSTEM AND METHOD FOR CALCINATING PLASTER |
CL2012000303A CL2012000303A1 (en) | 2009-08-07 | 2012-02-06 | System and procedure for calcining natural and synthetic gypsum or a combination of these, which includes a mill to grind and dry the gypsum, a rapid calciner to produce exhaust gas and calcined gypsum and a mechanism to transport at least a part of said gas to an air heater supplying hot gas to the calciner. |
IN2036DEN2012 IN2012DN02036A (en) | 2009-08-07 | 2012-03-07 |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
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US12/537,617 US7897134B1 (en) | 2009-08-07 | 2009-08-07 | System and method for calcining gypsum |
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US20110033351A1 true US20110033351A1 (en) | 2011-02-10 |
US7897134B1 US7897134B1 (en) | 2011-03-01 |
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US12/537,617 Active US7897134B1 (en) | 2009-08-07 | 2009-08-07 | System and method for calcining gypsum |
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US (1) | US7897134B1 (en) |
AR (1) | AR077602A1 (en) |
BR (1) | BR112012002703B1 (en) |
CL (1) | CL2012000303A1 (en) |
IN (1) | IN2012DN02036A (en) |
WO (1) | WO2011016912A1 (en) |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN102515594A (en) * | 2011-12-31 | 2012-06-27 | 四川宏达股份有限公司 | Gypsum powder calcination technology |
CN104003636A (en) * | 2014-06-12 | 2014-08-27 | 安玉奎 | Gypsum processing system |
CN108503247A (en) * | 2018-06-21 | 2018-09-07 | 四川方大新型建材科技开发有限责任公司 | Industry by-product gypsum produces the method and apparatus of high temperature gypsum |
CN113880471A (en) * | 2021-11-12 | 2022-01-04 | 天宝动物营养科技股份有限公司 | Preparation method of alpha-beta composite semi-hydrated gypsum |
WO2022256925A1 (en) * | 2021-06-09 | 2022-12-15 | Refratechnik Holding Gmbh | Production of calcined material with separate calcination of exhaust dust |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
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CN112266190B (en) * | 2020-10-30 | 2022-06-28 | 辽宁东大粉体工程技术有限公司 | Device and method for producing self-excited II type anhydrous gypsum by using industrial byproduct gypsum |
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US4569831A (en) * | 1985-04-01 | 1986-02-11 | Fuller Company | Process and apparatus for calcining gypsum |
US5437850A (en) * | 1991-03-25 | 1995-08-01 | Sulzer-Escher Wyss Gmbh | Method for calcining moist gypsum |
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FR2311764A1 (en) * | 1975-05-23 | 1976-12-17 | Rhone Poulenc Ind | METHOD AND APPARATUS FOR THERMAL TRANSFORMATION OF GYPSUM |
FR2836913B1 (en) * | 2002-03-08 | 2006-11-24 | Lafarge Platres | DEVICE FOR DRYING AND / OR COOKING GYPSUM |
US7621474B2 (en) * | 2006-03-14 | 2009-11-24 | National Gypsum Properties, Llc | Method and apparatus for calcining gypsum |
JP4657281B2 (en) * | 2007-12-28 | 2011-03-23 | 株式会社御池鐵工所 | Waste gypsum recycling plant and waste gypsum recycling method |
JP5439643B2 (en) * | 2008-02-19 | 2014-03-12 | ユナイテッド・ステイツ・ジプサム・カンパニー | Gypsum firing method |
EP2116294A1 (en) * | 2008-05-09 | 2009-11-11 | Claudius Peters Technologies GmbH | Calcination method and facility |
-
2009
- 2009-08-07 US US12/537,617 patent/US7897134B1/en active Active
-
2010
- 2010-06-23 BR BR112012002703-4A patent/BR112012002703B1/en active IP Right Grant
- 2010-06-23 WO PCT/US2010/039564 patent/WO2011016912A1/en active Application Filing
- 2010-07-28 AR ARP100102728A patent/AR077602A1/en active IP Right Grant
-
2012
- 2012-02-06 CL CL2012000303A patent/CL2012000303A1/en unknown
- 2012-03-07 IN IN2036DEN2012 patent/IN2012DN02036A/en unknown
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US3956456A (en) * | 1971-12-17 | 1976-05-11 | National Gypsum Company | Gypsum calcination |
US4569831A (en) * | 1985-04-01 | 1986-02-11 | Fuller Company | Process and apparatus for calcining gypsum |
US5437850A (en) * | 1991-03-25 | 1995-08-01 | Sulzer-Escher Wyss Gmbh | Method for calcining moist gypsum |
Cited By (5)
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CN102515594A (en) * | 2011-12-31 | 2012-06-27 | 四川宏达股份有限公司 | Gypsum powder calcination technology |
CN104003636A (en) * | 2014-06-12 | 2014-08-27 | 安玉奎 | Gypsum processing system |
CN108503247A (en) * | 2018-06-21 | 2018-09-07 | 四川方大新型建材科技开发有限责任公司 | Industry by-product gypsum produces the method and apparatus of high temperature gypsum |
WO2022256925A1 (en) * | 2021-06-09 | 2022-12-15 | Refratechnik Holding Gmbh | Production of calcined material with separate calcination of exhaust dust |
CN113880471A (en) * | 2021-11-12 | 2022-01-04 | 天宝动物营养科技股份有限公司 | Preparation method of alpha-beta composite semi-hydrated gypsum |
Also Published As
Publication number | Publication date |
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WO2011016912A1 (en) | 2011-02-10 |
IN2012DN02036A (en) | 2015-07-31 |
US7897134B1 (en) | 2011-03-01 |
CL2012000303A1 (en) | 2012-10-12 |
BR112012002703A2 (en) | 2016-04-19 |
BR112012002703A8 (en) | 2017-10-10 |
AR077602A1 (en) | 2011-09-07 |
BR112012002703B1 (en) | 2021-02-17 |
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