WO2022187903A1 - Method for calcination - Google Patents
Method for calcination Download PDFInfo
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- WO2022187903A1 WO2022187903A1 PCT/AU2022/050199 AU2022050199W WO2022187903A1 WO 2022187903 A1 WO2022187903 A1 WO 2022187903A1 AU 2022050199 W AU2022050199 W AU 2022050199W WO 2022187903 A1 WO2022187903 A1 WO 2022187903A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- hydrated alumina
- alumina
- energy
- calcination
- heating
- Prior art date
Links
- 238000000034 method Methods 0.000 title claims abstract description 354
- 238000001354 calcination Methods 0.000 title claims abstract description 88
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims abstract description 329
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 130
- 238000010438 heat treatment Methods 0.000 claims abstract description 113
- 238000007599 discharging Methods 0.000 claims abstract description 82
- 239000000126 substance Substances 0.000 claims abstract description 13
- 238000005381 potential energy Methods 0.000 claims abstract description 9
- 239000000463 material Substances 0.000 claims description 100
- 230000005611 electricity Effects 0.000 claims description 74
- 150000003839 salts Chemical class 0.000 claims description 53
- 238000011084 recovery Methods 0.000 claims description 42
- 230000000717 retained effect Effects 0.000 claims description 35
- 238000001035 drying Methods 0.000 claims description 32
- 239000007787 solid Substances 0.000 claims description 21
- 239000007788 liquid Substances 0.000 claims description 9
- 239000003921 oil Substances 0.000 claims description 8
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims description 6
- 229910052751 metal Inorganic materials 0.000 claims description 5
- 239000002184 metal Substances 0.000 claims description 5
- 150000001875 compounds Chemical class 0.000 claims description 4
- 150000002739 metals Chemical class 0.000 claims description 4
- 239000001569 carbon dioxide Substances 0.000 claims description 3
- 229910002092 carbon dioxide Inorganic materials 0.000 claims description 3
- 239000011435 rock Substances 0.000 claims description 2
- 230000003247 decreasing effect Effects 0.000 description 77
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 14
- 229910052799 carbon Inorganic materials 0.000 description 14
- FGIUAXJPYTZDNR-UHFFFAOYSA-N potassium nitrate Chemical compound [K+].[O-][N+]([O-])=O FGIUAXJPYTZDNR-UHFFFAOYSA-N 0.000 description 14
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 12
- 239000001257 hydrogen Substances 0.000 description 12
- 229910052739 hydrogen Inorganic materials 0.000 description 12
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 10
- 230000007423 decrease Effects 0.000 description 9
- 238000002485 combustion reaction Methods 0.000 description 8
- VWDWKYIASSYTQR-UHFFFAOYSA-N sodium nitrate Chemical compound [Na+].[O-][N+]([O-])=O VWDWKYIASSYTQR-UHFFFAOYSA-N 0.000 description 8
- 239000002028 Biomass Substances 0.000 description 7
- 238000001816 cooling Methods 0.000 description 7
- 238000002425 crystallisation Methods 0.000 description 7
- 239000012530 fluid Substances 0.000 description 7
- ZZUFCTLCJUWOSV-UHFFFAOYSA-N furosemide Chemical compound C1=C(Cl)C(S(=O)(=O)N)=CC(C(O)=O)=C1NCC1=CC=CO1 ZZUFCTLCJUWOSV-UHFFFAOYSA-N 0.000 description 7
- 239000013529 heat transfer fluid Substances 0.000 description 7
- 235000010333 potassium nitrate Nutrition 0.000 description 7
- 239000002002 slurry Substances 0.000 description 7
- -1 aluminium oxyhydroxide Chemical compound 0.000 description 6
- 230000000670 limiting effect Effects 0.000 description 6
- 239000000203 mixture Substances 0.000 description 6
- 230000008569 process Effects 0.000 description 6
- MHCVCKDNQYMGEX-UHFFFAOYSA-N 1,1'-biphenyl;phenoxybenzene Chemical compound C1=CC=CC=C1C1=CC=CC=C1.C=1C=CC=CC=1OC1=CC=CC=C1 MHCVCKDNQYMGEX-UHFFFAOYSA-N 0.000 description 5
- 230000018044 dehydration Effects 0.000 description 5
- 238000006297 dehydration reaction Methods 0.000 description 5
- 229910052782 aluminium Inorganic materials 0.000 description 4
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 4
- 239000012467 final product Substances 0.000 description 4
- 238000002844 melting Methods 0.000 description 4
- 230000008018 melting Effects 0.000 description 4
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 4
- 230000004048 modification Effects 0.000 description 4
- 238000012986 modification Methods 0.000 description 4
- 239000004323 potassium nitrate Substances 0.000 description 4
- 238000000926 separation method Methods 0.000 description 4
- 239000004317 sodium nitrate Substances 0.000 description 4
- 235000010344 sodium nitrate Nutrition 0.000 description 4
- LPXPTNMVRIOKMN-UHFFFAOYSA-M sodium nitrite Chemical compound [Na+].[O-]N=O LPXPTNMVRIOKMN-UHFFFAOYSA-M 0.000 description 4
- 230000007704 transition Effects 0.000 description 4
- 239000004411 aluminium Substances 0.000 description 3
- 229910001593 boehmite Inorganic materials 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 230000006835 compression Effects 0.000 description 3
- 238000007906 compression Methods 0.000 description 3
- 239000012141 concentrate Substances 0.000 description 3
- FAHBNUUHRFUEAI-UHFFFAOYSA-M hydroxidooxidoaluminium Chemical compound O[Al]=O FAHBNUUHRFUEAI-UHFFFAOYSA-M 0.000 description 3
- 230000036961 partial effect Effects 0.000 description 3
- 230000005855 radiation Effects 0.000 description 3
- 238000004131 Bayer process Methods 0.000 description 2
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 2
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 2
- 229910052783 alkali metal Inorganic materials 0.000 description 2
- 150000001340 alkali metals Chemical class 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 229910001570 bauxite Inorganic materials 0.000 description 2
- 229910052797 bismuth Inorganic materials 0.000 description 2
- 238000009835 boiling Methods 0.000 description 2
- 150000004649 carbonic acid derivatives Chemical class 0.000 description 2
- 239000003518 caustics Substances 0.000 description 2
- 150000001805 chlorine compounds Chemical class 0.000 description 2
- 230000029087 digestion Effects 0.000 description 2
- 239000000374 eutectic mixture Substances 0.000 description 2
- 150000004673 fluoride salts Chemical class 0.000 description 2
- 239000002803 fossil fuel Substances 0.000 description 2
- 239000000295 fuel oil Substances 0.000 description 2
- 150000002431 hydrogen Chemical class 0.000 description 2
- 239000003345 natural gas Substances 0.000 description 2
- 150000002823 nitrates Chemical class 0.000 description 2
- 150000002826 nitrites Chemical class 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- JTJMJGYZQZDUJJ-UHFFFAOYSA-N phencyclidine Chemical class C1CCCCN1C1(C=2C=CC=CC=2)CCCCC1 JTJMJGYZQZDUJJ-UHFFFAOYSA-N 0.000 description 2
- BITYAPCSNKJESK-UHFFFAOYSA-N potassiosodium Chemical compound [Na].[K] BITYAPCSNKJESK-UHFFFAOYSA-N 0.000 description 2
- 229910052700 potassium Inorganic materials 0.000 description 2
- 239000011591 potassium Substances 0.000 description 2
- PDEDQSAFHNADLV-UHFFFAOYSA-M potassium;disodium;dinitrate;nitrite Chemical class [Na+].[Na+].[K+].[O-]N=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O PDEDQSAFHNADLV-UHFFFAOYSA-M 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 229910052708 sodium Inorganic materials 0.000 description 2
- 239000011734 sodium Substances 0.000 description 2
- 235000010288 sodium nitrite Nutrition 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 1
- XFBXDGLHUSUNMG-UHFFFAOYSA-N alumane;hydrate Chemical compound O.[AlH3] XFBXDGLHUSUNMG-UHFFFAOYSA-N 0.000 description 1
- WNROFYMDJYEPJX-UHFFFAOYSA-K aluminium hydroxide Chemical compound [OH-].[OH-].[OH-].[Al+3] WNROFYMDJYEPJX-UHFFFAOYSA-K 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 125000004122 cyclic group Chemical group 0.000 description 1
- 230000007717 exclusion Effects 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 229910001679 gibbsite Inorganic materials 0.000 description 1
- 230000036571 hydration Effects 0.000 description 1
- 238000006703 hydration reaction Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 239000012768 molten material Substances 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000002829 reductive effect Effects 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F7/00—Compounds of aluminium
- C01F7/02—Aluminium oxide; Aluminium hydroxide; Aluminates
- C01F7/44—Dehydration of aluminium oxide or hydroxide, i.e. all conversions of one form into another involving a loss of water
- C01F7/441—Dehydration of aluminium oxide or hydroxide, i.e. all conversions of one form into another involving a loss of water by calcination
- C01F7/444—Apparatus therefor
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F7/00—Compounds of aluminium
- C01F7/02—Aluminium oxide; Aluminium hydroxide; Aluminates
- C01F7/44—Dehydration of aluminium oxide or hydroxide, i.e. all conversions of one form into another involving a loss of water
- C01F7/441—Dehydration of aluminium oxide or hydroxide, i.e. all conversions of one form into another involving a loss of water by calcination
Definitions
- the Bayer process is a cyclic process where bauxite ore is digested in a hot caustic solution to dissolve the alumina bearing minerals. Undissolved solids are separated and the liquor cooled to precipitate hydrated alumina also known as aluminium trihydroxide.
- the recovered hydrated alumina is heated at approximately 1000 °C to produce alumina, in a process known as calcination.
- alumina in addition to removal of the entrained water, water is a byproduct of the calcination reaction, as hydrated alumina produces aluminium trioxide (AI2O3) also known as alumina.
- AI2O3 aluminium trioxide
- the calcination reaction can produce a variety of distinct and measurable aluminous structures. These include aluminium trioxide structural forms and aluminium oxyhydroxide structural forms.
- the preferred composition of smelter grade alumina contains mostly the, so-called, gamma form, but also quantities of other alumina phases (e.g., alpha, kappa, chi, etc.).
- Calcination is an energy intensive process.
- the water released as steam from the hydrated alumina during calcination (-0.53 t water/t alumina) is lost to the atmosphere through the stacks together with its latent heat energy calcination (-1 .2 GJ/t alumina).
- alumina shall be understood to encompass all structural forms or phases of aluminium trioxide including gamma alumina.
- aluminium oxyhydroxide shall be understood to encompass all structural forms or phases of aluminium oxyhydroxide including boehmite.
- calcination shall be taken to encompass the complete or partial removal of the physically and chemically bound and unbound water entering with the hydrated alumina feed to the calciner.
- solution or variations such as “solutions”, will be understood to encompass slurries, suspensions and other mixtures containing undissolved and/or dissolved solids.
- a method for calcination of hydrated alumina comprising the steps of: heating the hydrated alumina in a dehydrating zone to reduce the water content of the hydrated alumina and provide partially calcined alumina; and heating the partially calcined alumina in a calcining zone to provide alumina, wherein the step of heating the hydrated alumina in a dehydrating zone uses at least in part, stored thermal energy, electrical energy, renewable energy or nuclear energy including combinations thereof and the step of heating the partially calcined alumina in a calcining zone uses at least in part, electrical energy or chemical potential energy including combinations thereof, and where the hydrated alumina is heated at least in part with stored thermal energy, the method is alternately operable in a thermal energy charging state and in a thermal energy discharging state.
- a method for calcination of hydrated alumina comprising the steps of: heating the hydrated alumina in a dehydrating zone to reduce the water content of the hydrated alumina and provide partially calcined alumina; and heating the partially calcined alumina in a calcining zone to provide alumina, wherein the step of heating the hydrated alumina in a dehydrating zone uses at least in part, stored thermal energy, electrical energy, renewable energy or nuclear energy including combinations thereof, and the step of heating the partially calcined alumina in a calcining zone uses at least in part, electrical energy or chemical potential energy including combinations thereof, wherein the stored thermal energy is provided by a thermal material and the method comprises the further step of: retaining thermal material in a retaining system prior to heating the hydrated alumina.
- the method is also alternately operable in a thermal energy steady state.
- a method for calcination of hydrated alumina comprising the steps of: heating the hydrated alumina in a dehydrating zone to reduce the water content of the hydrated alumina and provide partially calcined alumina; and heating the partially calcined alumina in a calcining zone to provide alumina, wherein the step of heating the hydrated alumina in a dehydrating zone uses at least in part, stored thermal energy, electrical energy, renewable energy or nuclear energy including combinations thereof and the step of heating the partially calcined alumina in a calcining zone uses at least in part, electrical energy or chemical potential energy including combinations thereof, and where the hydrated alumina is heated at least in part with stored thermal energy, the method is alternately operable in a net energy increasing state, and in a net energy decreasing state.
- the method is also alternately operable in a net energy steady state.
- hydrated alumina shall be understood to encompass all hydroxide and oxyhydroxide forms of aluminium including gibbsite and boehmite.
- the hydrated alumina, the partially calcined alumina and the alumina may be provided in numerous structural forms.
- partially calcined alumina shall be taken to encompass the complete or partial removal of the physically and chemically bound and unbound water.
- calcination of partially calcined alumina removes physically bound water followed by water of crystallisation. Partial removal of water of crystallisation can result in the formation of different aluminum-containing species including aluminium trioxide in a variety of structural forms and aluminium oxyhydroxide in a variety of structural forms. Aluminium trioxide structural forms may include gamma, alpha, kappa and chi.
- the partially calcined alumina may be provided with varying degrees of hydration.
- the partially calcined alumina is substantially aluminium monohydrate.
- the partially calcined alumina is boehmite.
- the term chemical potential energy shall be understood to refer to the energy stored in the chemical bonds of one or more substances.
- the chemical potential energy is provided in the form of aluminium powder. When contacted with steam, aluminium powder releases large amounts of energy in addition to hydrogen and alumina. Said energy may provide at least in part, energy for the calcination step.
- the chemical potential energy is provided in the form of combustion energy.
- combustion energy shall be understood to refer to energy resulting from combustion, a chemical reaction between two substances usually including oxygen.
- retaining the thermal material in a retaining system enables the stored thermal energy to be accessed as required.
- the thermal material is retained for at least 10 minutes. In one form of the invention, the thermal material is retained for at least 20 minutes. In one form of the invention, the thermal material is retained for at least 60 minutes. In one form of the invention, the thermal material is retained for at least 2 hours minutes. In one form of the invention, the thermal material is retained for at least 4 hours. In one form of the invention, the thermal material is retained for at least 8 hours. In one form of the invention, the thermal material is retained for at least 12 hours. In one form of the invention, the thermal material is retained for at least 24 hours. In one form of the invention, the thermal material is retained for at least 2 days.
- the thermal material is retained for at least 3 days. In one form of the invention, the thermal material is retained for at least 4 days. In one form of the invention, the thermal material is retained for at least 5 days. In one form of the invention, the thermal material is retained for at least 6 days. In one form of the invention, the thermal material is retained for at least 7 days. In one form of the invention, the thermal material is retained for at least 14 days.
- the thermal material is retained for up to 10 minutes. In one form of the invention, the thermal material is retained for up to 20 minutes. In one form of the invention, the thermal material is retained for up to 60 minutes. In one form of the invention, the thermal material is retained for up to 2 hours minutes. In one form of the invention, the thermal material is retained for at least up to 4 hours. In one form of the invention, the thermal material is retained for up to 8 hours. In one form of the invention, the thermal material is retained for up to 12 hours. In one form of the invention, the thermal material is retained for up to 24 hours. In one form of the invention, the thermal material is retained for up to 2 days. In one form of the invention, the thermal material is retained for up to 3 days.
- the thermal material is retained for up to 4 days. In one form of the invention, the thermal material is retained for up to 5 days. In one form of the invention, the thermal material is retained for up to 6 days. In one form of the invention, the thermal material is retained for up to 7 days. In one form of the invention, the thermal material is retained for up to 14 days.
- the method comprises the additional step of retaining sufficient stored thermal energy to accommodate continuous heating of the hydrated alumina for at least 10 minutes. In one form of the invention, the method comprises the additional step of retaining sufficient stored thermal energy to accommodate continuous heating of the hydrated alumina for at least 20 minutes. In one form of the invention, the method comprises the additional step of retaining sufficient stored thermal energy to accommodate continuous heating of the hydrated alumina for at least 30 minutes. In one form of the invention, the method comprises the additional step of retaining sufficient stored thermal energy to accommodate continuous heating of the hydrated alumina for at least 60 minutes. In one form of the invention, the method comprises the additional step of retaining sufficient stored thermal energy to accommodate continuous heating of the hydrated alumina for at least 1 hour.
- the method comprises the additional step of retaining sufficient stored thermal energy to accommodate continuous heating of the hydrated alumina for at least 2 hours. In one form of the invention, the method comprises the additional step of retaining sufficient stored thermal energy to accommodate continuous heating of the hydrated alumina for at least 4 hours. In one form of the invention, the method comprises the additional step of retaining sufficient stored thermal energy to accommodate continuous heating of the hydrated alumina for at least 6 hours. In one form of the invention, the method comprises the additional step of retaining sufficient stored thermal energy to accommodate continuous heating of the hydrated alumina for at least 12 hours. In one form of the invention, the method comprises the additional step of retaining sufficient stored thermal energy to accommodate continuous heating of the hydrated alumina for at least 24 hours.
- the method comprises the additional step of retaining sufficient stored thermal energy to accommodate continuous heating of the hydrated alumina for at least 1 day. In one form of the invention, the method comprises the additional step of retaining sufficient stored thermal energy to accommodate continuous heating of the hydrated alumina for at least 2 days. In one form of the invention, the method comprises the additional step of retaining sufficient stored thermal energy to accommodate continuous heating of the hydrated alumina for at least 3 days. In one form of the invention, the method comprises the additional step of retaining sufficient stored thermal energy to accommodate continuous heating of the hydrated alumina for at least 4 days. In one form of the invention, the method comprises the additional step of retaining sufficient stored thermal energy to accommodate continuous heating of the hydrated alumina for at least 5 days.
- the method comprises the additional step of retaining sufficient stored thermal energy to accommodate continuous heating of the hydrated alumina for at least 6 days. In one form of the invention, the method comprises the additional step of retaining sufficient stored thermal energy to accommodate continuous heating of the hydrated alumina for at least 7 days. In one form of the invention, the method comprises the additional step of retaining sufficient stored thermal energy to accommodate continuous heating of the hydrated alumina for at least 14 days.
- the method comprises the additional step of retaining sufficient stored thermal energy to accommodate continuous heating of the hydrated alumina for up to 10 minutes. In one form of the invention, the method comprises the additional step of retaining sufficient stored thermal energy to accommodate continuous heating of the hydrated alumina for up to 20 minutes. In one form of the invention, the method comprises the additional step of retaining sufficient stored thermal energy to accommodate continuous heating of the hydrated alumina for up to 30 minutes. In one form of the invention, the method comprises the additional step of retaining sufficient stored thermal energy to accommodate continuous heating of the hydrated alumina for up to 60 minutes. In one form of the invention, the method comprises the additional step of retaining sufficient stored thermal energy to accommodate continuous heating of the hydrated alumina for up to 1 hour.
- the method comprises the additional step of retaining sufficient stored thermal energy to accommodate continuous heating of the hydrated alumina for up to 2 hours. In one form of the invention, the method comprises the additional step of retaining sufficient stored thermal energy to accommodate continuous heating of the hydrated alumina for up to 4 hours. In one form of the invention, the method comprises the additional step of retaining sufficient stored thermal energy to accommodate continuous heating of the hydrated alumina for up to 6 hours. In one form of the invention, the method comprises the additional step of retaining sufficient stored thermal energy to accommodate continuous heating of the hydrated alumina for up to 12 hours. In one form of the invention, the method comprises the additional step of retaining sufficient stored thermal energy to accommodate continuous heating of the hydrated alumina for up to 24 hours.
- the method comprises the additional step of retaining sufficient stored thermal energy to accommodate continuous heating of the hydrated alumina for up to 1 day. In one form of the invention, the method comprises the additional step of retaining sufficient stored thermal energy to accommodate continuous heating of the hydrated alumina for up to 2 days. In one form of the invention, the method comprises the additional step of retaining sufficient stored thermal energy to accommodate continuous heating of the hydrated alumina for up to 3 days. In one form of the invention, the method comprises the additional step of retaining sufficient stored thermal energy to accommodate continuous heating of the hydrated alumina for up to 4 days. In one form of the invention, the method comprises the additional step of retaining sufficient stored thermal energy to accommodate continuous heating of the hydrated alumina for up to 5 days.
- the method comprises the additional step of retaining sufficient stored thermal energy to accommodate continuous heating of the hydrated alumina for up to 6 days. In one form of the invention, the method comprises the additional step of retaining sufficient stored thermal energy to accommodate continuous heating of the hydrated alumina for up to 7 days. In one form of the invention, the method comprises the additional step of retaining sufficient stored thermal energy to accommodate continuous heating of the hydrated alumina for up to 14 days.
- the step of operating the method in a thermal energy charging state continues for at least 10 minutes before operating the method in a thermal energy discharging state. In one form of the invention, the step of operating the method in a thermal energy charging state continues for at least 20 minutes before operating the method in a thermal energy discharging state. In one form of the invention, the step of operating the method in a thermal energy charging state continues for at least 60 minutes before operating the method in a thermal energy discharging state. In one form of the invention, the step of operating the method in a thermal energy charging state continues for at least 2 hours before operating the method in a thermal energy discharging state.
- the step of operating the method in a thermal energy charging state continues for at least 4 hours before operating the method in a thermal energy discharging state. In one form of the invention, the step of operating the method in a thermal energy charging state continues for at least 8 hours before operating the method in a thermal energy discharging state. In one form of the invention, the step of operating the method in a thermal energy charging state continues for at least 12 hours before operating the method in a thermal energy discharging state. In one form of the invention, the step of operating the method in a thermal energy charging state continues for at least 24 hours before operating the method in a thermal energy discharging state.
- the step of operating the method in a thermal energy charging state continues for at least 2 days before operating the method in a thermal energy discharging state. In one form of the invention, the step of operating the method in a thermal energy charging state continues for at least 3 days before operating the method in a thermal energy discharging state. In one form of the invention, the step of operating the method in a thermal energy charging state continues for at least 4 days before operating the method in a thermal energy discharging state.
- the step of operating the method in a thermal energy charging state continues for at least 5 days before operating the method in a thermal energy discharging state. In one form of the invention, the step of operating the method in a thermal energy charging state continues for at least 6 days before operating the method in a thermal energy discharging state. In one form of the invention, the step of operating the method in a thermal energy charging state continues for at least 7 days before operating the method in a thermal energy discharging state. In one form of the invention, the step of operating the method in a thermal energy charging state continues for at least 14 days before operating the method in a thermal energy discharging state.
- the step of operating the method in a thermal energy charging state continues for up to 10 minutes before operating the method in a thermal energy discharging state. In one form of the invention, the step of operating the method in a thermal energy charging state continues for up to 20 minutes before operating the method in a thermal energy discharging state. In one form of the invention, the step of operating the method in a thermal energy charging state continues for up to 60 minutes before operating the method in a thermal energy discharging state. In one form of the invention, the step of operating the method in a thermal energy charging state continues for up 1 to hour before operating the method in a thermal energy discharging state.
- the step of operating the method in a thermal energy charging state continues for up to 2 hours before operating the method in a thermal energy discharging state. In one form of the invention, the step of operating the method in a thermal energy charging state continues for up to 4 hours before operating the method in a thermal energy discharging state. In one form of the invention, the step of operating the method in a thermal energy charging state continues for up to 8 hours before operating the method in a thermal energy discharging state. In one form of the invention, the step of operating the method in a thermal energy charging state continues for up to 12 hours before operating the method in a thermal energy discharging state.
- the step of operating the method in a thermal energy charging state continues for up to 24 hours before operating the method in a thermal energy discharging state. In one form of the invention, the step of operating the method in a thermal energy charging state continues for up to 2 days before operating the method in a thermal energy discharging state. In one form of the invention, the step of operating the method in a thermal energy charging state continues for up to 3 days before operating the method in a thermal energy discharging state. In one form of the invention, the step of operating the method in a thermal energy charging state continues for up to 4 days before operating the method in a thermal energy discharging state.
- the step of operating the method in a thermal energy charging state continues for up to 5 days before operating the method in a thermal energy discharging state. In one form of the invention, the step of operating the method in a thermal energy charging state continues for up to 6 days before operating the method in a thermal energy discharging state. In one form of the invention, the step of operating the method in a thermal energy charging state continues for up to 7 days before operating the method in a thermal energy discharging state. In one form of the invention, the step of operating the method in a thermal energy charging state continues for up to 14 days before operating the method in a thermal energy discharging state.
- the step of operating the method in a thermal energy discharging state continues for at least 10 minutes before operating the method in a thermal energy charging state. In one form of the invention, the step of operating the method in a thermal energy discharging state continues for at least 20 minutes before operating the method in a thermal energy charging state. In one form of the invention, the step of operating the method in a thermal energy discharging state continues for at least 60 minutes before operating the method in a thermal energy charging state. In one form of the invention, the step of operating the method in a thermal energy discharging state continues for at least 2 hours before operating the method in a thermal energy charging state.
- the step of operating the method in a thermal energy discharging state continues for at least 4 hours before operating the method in a thermal energy charging state. In one form of the invention, the step of operating the method in a thermal energy discharging state continues for at least 8 hours before operating the method in a thermal energy charging state. In one form of the invention, the step of operating the method in a thermal energy discharging state continues for at least 12 hours before operating the method in a thermal energy charging state. In one form of the invention, the step of operating the method in a thermal energy discharging state continues for at least 24 hours before operating the method in a thermal energy charging state.
- the step of operating the method in a thermal energy discharging state continues for at least 2 days before operating the method in a thermal energy charging state. In one form of the invention, the step of operating the method in a thermal energy discharging state continues for at least 3 days before operating the method in a thermal energy charging state. In one form of the invention, the step of operating the method in a thermal energy discharging state continues for at least 4 days before operating the method in a thermal energy charging state. In one form of the invention, the step of operating the method in a thermal energy discharging state continues for at least 5 days before operating the method in a thermal energy charging state.
- the step of operating the method in a thermal energy discharging state continues for at least 6 days before operating the method in a thermal energy charging state. In one form of the invention, the step of operating the method in a thermal energy discharging state continues for at least 7 days before operating the method in a thermal energy charging state. In one form of the invention, the step of operating the method in a thermal energy discharging state continues for at least 14 days before operating the method in a thermal energy charging state.
- the step of operating the method in a thermal energy discharging state continues for up to 10 minutes before operating the method in a thermal energy charging state. In one form of the invention, the step of operating the method in a thermal energy discharging state continues for up to 20 minutes before operating the method in a thermal energy charging state. In one form of the invention, the step of operating the method in a thermal energy discharging state continues for up to 60 minutes before operating the method in a thermal energy charging state. In one form of the invention, the step of operating the method in a thermal energy discharging state continues for up 1 to hour before operating the method in a thermal energy charging state.
- the step of operating the method in a thermal energy discharging state continues for up to 2 hours before operating the method in a thermal energy charging state. In one form of the invention, the step of operating the method in a thermal energy discharging state continues for up to 4 hours before operating the method in a thermal energy charging state. In one form of the invention, the step of operating the method in a thermal energy discharging state continues for up to 8 hours before operating the method in a thermal energy charging state. In one form of the invention, the step of operating the method in a thermal energy discharging state continues for up to 12 hours before operating the method in a thermal energy charging state.
- the step of operating the method in a thermal energy discharging state continues for up to 24 hours before operating the method in a thermal energy charging state. In one form of the invention, the step of operating the method in a thermal energy discharging state continues for up to 2 days before operating the method in a thermal energy charging state. In one form of the invention, the step of operating the method in a thermal energy discharging state continues for up to 3 days before operating the method in a thermal energy charging state. In one form of the invention, the step of operating the method in a thermal energy discharging state continues for up to 4 days before operating the method in a thermal energy charging state.
- the step of operating the method in a thermal energy discharging state continues for up to 5 days before operating the method in a thermal energy charging state. In one form of the invention, the step of operating the method in a thermal energy discharging state continues for up to 6 days before operating the method in a thermal energy charging state. In one form of the invention, the step of operating the method in a thermal energy discharging state continues for up to 7 days before operating the method in a thermal energy charging state. In one form of the invention, the step of operating the method in a thermal energy discharging state continues for up to 14 days before operating the method in a thermal energy charging state.
- the step of operating the method in a net energy increasing state continues for at least 10 minutes before operating the method in a net energy decreasing state. In one form of the invention, the step of operating the method in a net energy increasing state continues for at least 20 minutes before operating the method in a net energy decreasing state. In one form of the invention, the step of operating the method in a net energy increasing state continues for at least 60 minutes before operating the method in a net energy decreasing state. In one form of the invention, the step of operating the method in a net energy increasing state continues for at least 2 hours before operating the method in a net energy decreasing state.
- the step of operating the method in a net energy increasing state continues for at least 4 hours before operating the method in a net energy decreasing state. In one form of the invention, the step of operating the method in a net energy increasing state continues for at least 8 hours before operating the method in a net energy decreasing state. In one form of the invention, the step of operating the method in a net energy increasing state continues for at least 12 hours before operating the method in a net energy decreasing state. In one form of the invention, the step of operating the method in a net energy increasing state continues for at least 24 hours before operating the method in a net energy decreasing state. In one form of the invention, the step of operating the method in a net energy increasing state continues for at least 2 days before operating the method in a net energy decreasing state.
- the step of operating the method in a net energy increasing state continues for at least 3 days before operating the method in a net energy decreasing state. In one form of the invention, the step of operating the method in a net energy increasing state continues for at least 4 days before operating the method in a net energy decreasing state. In one form of the invention, the step of operating the method in a net energy increasing state continues for at least 5 days before operating the method in a net energy decreasing state. In one form of the invention, the step of operating the method in a net energy increasing state continues for at least 6 days before operating the method in a net energy decreasing state. In one form of the invention, the step of operating the method in a net energy increasing state continues for at least 7 days before operating the method in a net energy decreasing state. In one form of the invention, the step of operating the method in a net energy increasing state continues for at least 14 days before operating the method in a net energy decreasing state.
- the step of operating the method in a net energy increasing state continues for up to 10 minutes before operating the method in a net energy decreasing state. In one form of the invention, the step of operating the method in a net energy increasing state continues for up to 20 minutes before operating the method in a net energy decreasing state. In one form of the invention, the step of operating the method in a net energy increasing state continues for up to 60 minutes before operating the method in a net energy decreasing state. In one form of the invention, the step of operating the method in a net energy increasing state continues for up 1 to hour before operating the method in a net energy decreasing state.
- the step of operating the method in a net energy increasing state continues for up to 2 hours before operating the method in a net energy decreasing state. In one form of the invention, the step of operating the method in a net energy increasing state continues for up to 4 hours before operating the method in a net energy decreasing state. In one form of the invention, the step of operating the method in a net energy increasing state continues for up to 8 hours before operating the method in a net energy decreasing state. In one form of the invention, the step of operating the method in a net energy increasing state continues for up to 12 hours before operating the method in a net energy decreasing state. In one form of the invention, the step of operating the method in a net energy increasing state continues for up to 24 hours before operating the method in a net energy decreasing state.
- the step of operating the method in a net energy increasing state continues for up to 2 days before operating the method in a net energy decreasing state. In one form of the invention, the step of operating the method in a net energy increasing state continues for up to 3 days before operating the method in a net energy decreasing state. In one form of the invention, the step of operating the method in a net energy increasing state continues for up to 4 days before operating the method in a net energy decreasing state. In one form of the invention, the step of operating the method in a net energy increasing state continues for up to 5 days before operating the method in a net energy decreasing state. In one form of the invention, the step of operating the method in a net energy increasing state continues for up to 6 days before operating the method in a net energy decreasing state.
- the step of operating the method in a net energy increasing state continues for up to 7 days before operating the method in a net energy decreasing state. In one form of the invention, the step of operating the method in a net energy increasing state continues for up to 14 days before operating the method in a net energy decreasing state.
- the step of operating the method in a net energy decreasing state continues for at least 10 minutes before operating the method in a net energy increasing state. In one form of the invention, the step of operating the method in a net energy decreasing state continues for at least 20 minutes before operating the method in a net energy increasing state. In one form of the invention, the step of operating the method in a net energy decreasing state continues for at least 60 minutes before operating the method in a net energy increasing state. In one form of the invention, the step of operating the method in a net energy decreasing state continues for at least 2 hours before operating the method in a net energy increasing state.
- the step of operating the method in a net energy decreasing state continues for at least 4 hours before operating the method in a net energy increasing state. In one form of the invention, the step of operating the method in a net energy decreasing state continues for at least 8 hours before operating the method in a net energy increasing state. In one form of the invention, the step of operating the method in a net energy decreasing state continues for at least 12 hours before operating the method in a net energy increasing state. In one form of the invention, the step of operating the method in a net energy decreasing state continues for at least 24 hours before operating the method in a net energy increasing state. In one form of the invention, the step of operating the method in a net energy decreasing state continues for at least 2 days before operating the method in a net energy increasing state.
- the step of operating the method in a net energy decreasing state continues for at least 3 days before operating the method in a net energy increasing state. In one form of the invention, the step of operating the method in a net energy decreasing state continues for at least 4 days before operating the method in a net energy increasing state. In one form of the invention, the step of operating the method in a net energy decreasing state continues for at least 5 days before operating the method in a net energy increasing state. In one form of the invention, the step of operating the method in a net energy decreasing state continues for at least 6 days before operating the method in a net energy increasing state. In one form of the invention, the step of operating the method in a net energy decreasing state continues for at least 7 days before operating the method in a net energy increasing state. In one form of the invention, the step of operating the method in a net energy decreasing state continues for at least 14 days before operating the method in a net energy increasing state.
- the step of operating the method in a net energy decreasing state continues for up to 10 minutes before operating the method in a net energy increasing state. In one form of the invention, the step of operating the method in a net energy decreasing state continues for up to 20 minutes before operating the method in a net energy increasing state. In one form of the invention, the step of operating the method in a net energy decreasing state continues for up to 60 minutes before operating the method in a net energy increasing state. In one form of the invention, the step of operating the method in a net energy decreasing state continues for up 1 to hour before operating the method in a net energy increasing state.
- the step of operating the method in a net energy decreasing state continues for up to 2 hours before operating the method in a net energy increasing state. In one form of the invention, the step of operating the method in a net energy decreasing state continues for up to 4 hours before operating the method in a net energy increasing state. In one form of the invention, the step of operating the method in a net energy decreasing state continues for up to 8 hours before operating the method in a net energy increasing state. In one form of the invention, the step of operating the method in a net energy decreasing state continues for up to 12 hours before operating the method in a net energy increasing state. In one form of the invention, the step of operating the method in a net energy decreasing state continues for up to 24 hours before operating the method in a net energy increasing state.
- the step of operating the method in a net energy decreasing state continues for up to 2 days before operating the method in a net energy increasing state. In one form of the invention, the step of operating the method in a net energy decreasing state continues for up to 3 days before operating the method in a net energy increasing state. In one form of the invention, the step of operating the method in a net energy decreasing state continues for up to 4 days before operating the method in a net energy increasing state. In one form of the invention, the step of operating the method in a net energy decreasing state continues for up to 5 days before operating the method in a net energy increasing state. In one form of the invention, the step of operating the method in a net energy decreasing state continues for up to 6 days before operating the method in a net energy increasing state.
- the step of operating the method in a net energy decreasing state continues for up to 7 days before operating the method in a net energy decreasing state. In one form of the invention, the step of operating the method in a net energy decreasing state continues for up to 14 days before operating the method in a net energy decreasing state.
- electricity may be drawn from an external supply.
- electricity may be drawn from an external supply.
- the electricity is drawn for a period that is suitable. Suitability may be determined by a number of factors including price, availability, demand or by agreement.
- Electricity availability may be relevant where the electricity is derived from renewable sources. Some renewable energy sources such as solar and wind are not generally continuously available.
- Local electricity demand can impact electricity supply from a grid. During periods of high demand, sufficient electricity may not be available to operate the thermal energy charging state or the net energy increasing state.
- Local electricity supply may be classified according to demand with the price being reflective thereof. For example, periods of high demand may be classified as peak demand or peak electricity and may be associated with higher prices. Periods of high demand may be classified as off-peak demand or off-peak electricity and may be associated with lower prices. There may further be periods between high and low demand, referred to as shoulder periods with intermediate pricing.
- off-peak electricity will be impacted by the relevant regulatory electricity supply. For example, over a 24 hour period, there may be one period of off-peak electricity supply or there may be two or more. In addition, either side of the off-peak period, there may be shoulder periods. The availability of off-peak electricity may be different on weekends and on working days. It may also change with the seasons of the year.
- the electricity supply in Perth, Western Australia from Monday to Friday is charged at peak prices from 3 pm to 9 pm, at off-peak prices from 9 pm until 7 am and at shoulder prices from 7 am to 3 pm.
- Operating the method of the present invention in Perth, Western Australia may entail operating the thermal energy charging state from 9 pm until 7 am thereby stockpiling hot thermal material. During this time, hot thermal material may still be used to heat the hydrated alumina.
- the electricity supply to the thermal material can be reduced or terminated and the system can run from 7 am until 9 pm in the thermal energy discharging state. During this period, energy to heat the hydrated alumina is provided by the stockpiled thermal material.
- the external electricity supply may be gradually decreased.
- the method will transition from the thermal energy charging state to the thermal energy discharging state transitioning through the steady state as it does so.
- the external electricity supply may be gradually increased. As the electricity supply increases, the method will transition from the thermal energy discharging state to the thermal energy charging state transitioning through the steady state as it does so.
- the external electricity supply may be gradually decreased. As the electricity supply decreases, the method will transition from the net energy increasing state to the net energy decreasing state transitioning through the steady state as it does so.
- the external electricity supply may be gradually increased. As the electricity supply increases, the method will transition from the net energy decreasing state to the net energy increasing state transitioning through the steady state as it does so.
- the thermal energy may be provided in the form of a heated thermal material.
- the thermal material may indirectly or directly heat the hydrated alumina.
- the stored thermal energy may be provided in the form of heat that is either sensible or latent. Sensible heat corresponds to thermal storage in a single phase where the temperature of the thermal material varies with the amount of stored energy.
- the thermal material may be provided as a liquid or a solid.
- a liquid thermal material include carbon dioxide, water, oil, molten metals such as molten sodium, molten potassium or molten eutectic mixtures of sodium- potassium or lead-bismuth and molten salts.
- molten metals such as molten sodium, molten potassium or molten eutectic mixtures of sodium- potassium or lead-bismuth and molten salts.
- a solid thermal material include non-molten salts, rock, metal or non-molten compounds such as alumina or partially calcined alumina.
- the thermal material may be provided in the form of an organic fluid such as an oil. It will be appreciated that an organic fluid must have appropriate operating temperature.
- a suitable fluid is Dowtherm ® A from Dow ® .
- the thermal material is a molten salt.
- molten salts have high boiling points, low viscosity, low vapour pressure and high volumetric heat capacities.
- the molten salt is an ionic salt of an alkali metal such as those comprising fluorides, chlorides, carbonates, nitrates, nitrites. It will be appreciated that the molten salt may contain more than one salt.
- Suitable salts include sodium nitrate NaNC>3 and potassium nitrate KNO3 which have melting points between 300-500°C and volumetric heat capacities between 1670 - 3770 kJ/m 3o C.
- Sodium hydroxide NaOH has a melting point of 320 °C and can be used up to 800 °C, but is highly corrosive.
- Solar salt, 60 % NaNC>3 and 40 % KNO3 may also be used.
- Commercially available "HITEC" salt consists of potassium nitrate (53 % by weight), sodium nitrite NaNC>2 (40 % by weight), and sodium nitrate (7 % by weight) with a liquid temperature range of 149 - 538 °C.
- the thermal material may be heated with electrical energy, renewable energy, nuclear energy or combinations thereof.
- the stored thermal energy results from heating the thermal material directly or indirectly with electricity.
- the step of heating the thermal material with electricity utilises off- peak electricity.
- At least a portion of the electricity is generated from a renewable power source and/or a nuclear energy source.
- Renewable power sources may include wind, solar, hydro, tidal, geothermal, biomass and hydrogen.
- the electricity is generated from nuclear energy.
- all of the electricity is generated from a renewable power source
- the electricity is sourced from a supply grid. At least a portion of the supply grid electricity may be generated from renewable power sources and/or nuclear energy sources. Renewable power sources may include wind, solar, hydro, tidal, geothermal, biomass and hydrogen.
- the thermal material is heated directly with energy from a renewable energy source.
- the thermal material is heated with solar energy using with solar towers or solar troughs to concentrate the solar radiation for direct use on hydrated alumina.
- thermal materials can retain their heat for a number of hours without (continuous) energy input.
- electricity to the thermal material can be shut off without significant temperature reduction.
- Peak electricity demand is generally in the early evening, such as between 5 pm and 8 pm. Understanding that larger volumes of molten material can retain heat for longer periods, it is believed that a three or four hour period can be compensated for.
- the stored thermal energy has a carbon intensity of less than 0.5 t CC MWhr.
- the electricity has a carbon intensity of less than 0.4 t CCWMWhr.
- the electricity has a carbon intensity of less than 0.3 t CCWMWhr.
- the electricity has a carbon intensity of less than 0.2 t CCWMWhr.
- the electricity has a carbon intensity of less than 0.1 t CCWMWhr.
- the method of the present invention may decrease the carbon output of the alumina refinery.
- the term decrease shall be understood to encompass reducing the carbon output relative to an equivalent alumina refinery solely utilising fossil fuel fired calcination as is known in the art.
- the term decrease shall also be understood to encompass the retrofit of an existing alumina refinery with the present invention as well as the construction of a new alumina refinery with the present invention.
- a heat transfer medium to transfer the heat from the thermal material to the hydrated alumina.
- the use of a heat transfer medium is particularly applicable where the thermal material is a solid such as alumina.
- the thermal material may be heated with electrical energy, renewable energy, nuclear energy or combinations thereof.
- the heat transfer medium is preferably provided as a fluid.
- a heat transfer medium include gases such as carbon dioxide, water, oil, molten metals such as molten sodium, molten potassium or molten eutectic mixtures of sodium-potassium or lead-bismuth and molten salts.
- the heat transfer medium may be provided in the form of an organic fluid such as an oil. It will be appreciated that an organic fluid must have appropriate operating temperature.
- a suitable fluid is Dowtherm ® A from Dow ® .
- the heat transfer medium is a molten salt.
- molten salts have high boiling points, low viscosity, low vapour pressure and high volumetric heat capacities.
- the molten salt is an ionic salt of an alkali metal such as those comprising fluorides, chlorides, carbonates, nitrates, nitrites. It will be appreciated that the molten salt may contain more than one salt.
- Suitable salts include sodium nitrate NaNC>3 and potassium nitrate KNO3 which have melting points between 300-500°C and volumetric heat capacities between 1670 - 3770 kJ/m 3o C.
- Sodium hydroxide NaOH has a melting point of 320 °C and can be used up to 800 °C, but is highly corrosive.
- HITEC salt consists of potassium nitrate (53 % by weight), sodium nitrite NaNC (40 % by weight), and sodium nitrate (7 % by weight) with a liquid temperature range of 149 - 538 °C.
- the heat transfer medium is heated by the thermal material.
- the heat transfer medium is heated using electricity.
- the step of heating the heat transfer medium utilises off-peak electricity.
- At least a portion of the electricity is generated from a renewable power source and/or a nuclear energy source.
- Renewable power sources may include wind, solar, hydro, tidal, geothermal, biomass and hydrogen.
- the electricity is generated from nuclear energy.
- all of the electricity is generated from a renewable power source
- the electricity is sourced from a supply grid. At least a portion of the supply grid electricity may be generated from renewable power sources and/or nuclear energy sources. Renewable power sources may include wind, solar, hydro, tidal, geothermal, biomass and hydrogen.
- the step of heating the heat transfer medium uses at least in part, stored thermal energy, electrical energy, renewable energy sources or nuclear energy
- the heat transfer medium is heated directly with energy from a renewable energy source.
- the heat transfer medium is heated with solar energy using with solar towers or solar troughs to concentrate the solar radiation for direct use on hydrated alumina.
- the retaining system may be provided in the form of one or more storage vessels.
- Retaining the thermal material in at least one storage vessel may include monitoring the temperature of the thermal material for the period of time the thermal material is retained in at least one storage vessel. It will be appreciated that the temperature of the thermal material should not drop significantly during the period of time the thermal material is retained in the at least one storage vessel.
- the mass of the thermal material in the at least one storage vessel should have sufficient heat capacity to account for periods of time where the energy supply for heating the thermal material is interrupted.
- the thermal material is retained in at least one vessel prepared from materials with appropriate chemical and thermal resistivity.
- materials with appropriate chemical and thermal resistivity For example, stainless steel is expected to be appropriate for a molten salt up to about 600 °C. At higher temperatures, a refractory lining would be considered.
- the storage vessel may be provided with electrical heating elements.
- the two storage vessels are adapted to retain thermal material at different temperatures.
- the storage vessel adapted to retain thermal material at the lower of the two temperatures is designated the low temperature storage vessel and the storage vessel adapted to retain thermal material at the higher of the two temperatures is designated the high temperature storage vessel.
- the hotter thermal material is adapted for heating the hydrated alumina in a dehydrating zone. It will be appreciated that the step of heating the hydrated alumina in a dehydrating zone decreases the temperature of the thermal material. After the step of heating the hydrated alumina in a dehydrating zone, this cooled thermal material is transferred to the low temperature storage vessel. [0092]
- the hydrated alumina may be heated directly or indirectly with electrical energy. Where the hydrated alumina is heated with electrical energy, the electrical energy may be used to heat electrical elements in direct contact with the hydrated alumina.
- the step of heating the hydrated alumina with electrical energy utilises off-peak electricity.
- At least a portion of the electrical energy is generated from a renewable power source and/or a nuclear energy source.
- Renewable power sources may include wind, solar, hydro, tidal, geothermal, biomass and hydrogen.
- the electricity is generated from nuclear energy.
- all of the electrical energy is generated from a renewable power source.
- the electrical energy is sourced from a supply grid. At least a portion of the supply grid electrical energy may be generated from renewable power sources and/or nuclear energy sources. Renewable power sources may include wind, solar, hydro, tidal, geothermal, biomass and hydrogen.
- Storage may be provided in the form of a battery.
- the hydrated alumina is heated directly with energy from a renewable energy source.
- the hydrated alumina is heated with solar energy using with solar towers or solar troughs to concentrate the solar radiation for direct use on hydrated alumina.
- the step of heating the hydrated alumina in a dehydrating zone is conducted at a temperature of between 250 °C and 600 °C. More preferably, the step of heating the hydrated alumina in a dehydrating zone is conducted at a temperature of between 350 °C and 500 °C. In one form of the invention, the step of heating the hydrated alumina in a dehydrating zone is conducted at a temperature of about 450 °C. [00101 ] In one form of the invention, the step of: heating the hydrated alumina in a dehydrating zone, is conducted under a pressure greater than atmospheric pressure.
- the pressure is preferably about 600 -1000 kPa gauge. More preferably, the pressure is about 700 - 850 kPa gauge. It will be appreciated that high temperature refineries may operate at higher pressure up to 7000 kPa.
- the hydrated alumina is indirectly heated with an indirect heat exchanger.
- Suitable indirect heat exchangers include shell and tube heaters and plate heat exchangers.
- the hydrated alumina may be heated in a fluidised bed. Alternatively, or in addition thereto, the hydrated alumina may be heated with electrical elements.
- the step of heating the partially calcined alumina in a calcining zone is conducted at a temperature of between 500 °C and 1200 °C.
- the step of heating the partially calcined alumina in a calcining zone is conducted at a temperature of between 500°C and 1000 °C. In one form of the invention, the step of heating the partially calcined alumina in a calcining zone is conducted at a temperature of between 500°C and 900 °C. In one form of the invention, the step of heating the partially calcined alumina in a calcining zone is conducted at a temperature of between 500°C and 800 °C. In one form of the invention, the step of heating the partially calcined alumina in a calcining zone is conducted at a temperature of between 500°C and 700 °C. In one form of the invention, the step of heating the partially calcined alumina in a calcining zone is conducted at a temperature of between 500°C and 600 °C.
- the step of heating the partially calcined alumina in a calcining zone may not calcine all of the partially calcined alumina.
- the step of heating the partially calcined alumina in a calcining zone may be conducted at lower temperatures than in traditional calcination.
- the concentrated steam that evolves can act as a mineraliser to lower the temperature required for calcination.
- the step of: heating the partially calcined alumina in a calcining zone is conducted under a pressure greater than atmospheric pressure.
- the step of heating the partially calcined alumina in a calcining zone is conducted under a pressure greater than atmospheric pressure
- the pressure is preferably about 600 - 1000 kPa gauge. More preferably, the pressure is about 700 - 850 kPa gauge.
- the partially calcined alumina is directly heated with electricity, for example, with electrical elements.
- partially calcined alumina is heated by combustion, for example, with hydrogen, natural gas or fuel oils or combinations thereof.
- the partially calcined alumina may be heated in a fluidised bed.
- the fluidised bed is preferably heated with electrically heated elements.
- the method comprises the additional step of: heating the hydrated alumina in a drying zone prior to the step of heating the hydrated alumina in a dehydrating zone.
- the step of heating the hydrated alumina in a drying zone is conducted at a temperature of between 100 °C and 300 °C. More preferably, the step of heating the hydrated alumina in a dehydrating zone is conducted at a temperature of between 150 °C and 250 °C. In one form of the invention, the step of drying the hydrated alumina in a dehydrating zone is conducted at a temperature of about 190 °C.
- the step of: heating the hydrated alumina in a drying zone is conducted under a pressure greater than atmospheric pressure.
- the step of heating the hydrated alumina in a drying zone is conducted under a pressure greater than atmospheric pressure
- the pressure is preferably about 600 - 1000 kPa gauge. More preferably, the pressure is about 700 - 850 kPa gauge.
- the step of drying the hydrated alumina may remove at least some free water and may remove some water of crystallisation.
- the step of heating the hydrated alumina in a drying zone may remove at least some free water and may remove some water of crystallisation.
- the step of heating the hydrated alumina in a drying zone will generate water vapour.
- Said water vapour may be utilised in the Bayer refinery where appropriate, depending on the pressure and temperature.
- the water vapour is compressed up to about 800 kPa and 220 °C and returned to the refinery.
- the water vapour is recycled to the drying zone to facilitate the step of drying the hydrated alumina.
- the water vapour is used to fluidise the solids in the dehydration zone, the calcining zone, and/or recycled to fluidise the solids in the drying zone.
- the water vapour may need to be compressed to be utilised.
- the step of compressing the water vapour is performed by mechanical vapour recompression.
- the step of heating the hydrated alumina in a dehydrating zone will generate water vapour.
- Said water vapour may be utilised in the Bayer refinery where appropriate, depending on the pressure and temperature.
- the water vapour is compressed up to about 800 kPa and 220 °C and returned to the refinery.
- the water vapour may be compressed up to about 6000 kPa and 300 °C.
- the water vapour is passed to the drying zone to facilitate the step of drying the hydrated alumina.
- the water vapour is used to fluidise the solids in the drying zone, the calcining zone, and/or recycled to fluidise the solids in the dehydration zone.
- the water vapour may need to be compressed to be utilised.
- the step of compressing the water vapour is performed by mechanical vapour recompression
- the step of calcining the partially calcined alumina will generate water vapour.
- Said water vapour may be utilised in the Bayer refinery where appropriate, depending on the pressure and temperature.
- the water vapour is compressed up to about 800 kPa and 220 °C and returned to the refinery.
- the water vapour is passed to the drying zone and/or the dehydrating zone.
- the water vapour is used to fluidise the solids in the drying zone, the dehydration zone, and/or recycled to fluidise the solids in the calcining zone.
- the water vapour may need to be compressed to be utilised.
- the step of compressing the water vapour is performed by mechanical vapour recompression
- Generated water vapour may be treated, returned to the refinery or used elsewhere in calcination.
- the step of treating the captured water vapour may comprise compressing the captured water vapour.
- the step of compressing the captured water vapour may be repeated. There may be a plurality of compression steps to attain the desired water vapour condensing temperature. [00130]
- the step of compressing the captured water vapour is performed by mechanical vapour recompression.
- mechanical vapour recompression reduces reliance on fossil fuel generated sources of heat to provide high condensing temperature steam.
- Mechanical vapour compression may be performed by centrifugal compressors, axial flow compressors or turbo compressors. Centrifugal compressors may be classified as high speed or low speed compressors.
- a power source is required to compress the captured water vapour.
- said power source is a low carbon power source.
- the power source is a renewable power source.
- the electricity is generated from a renewable power source.
- Renewable power sources may include wind, solar, hydro, tidal, geothermal, biomass and hydrogen.
- the electricity is generated from a zero carbon power source such as hydrogen or nuclear.
- the electricity may be stored in a battery after generation and prior to use.
- the compressor is electrically powered with electricity with a carbon intensity of less than 0.5 t CCWMWhr.
- the electricity has a carbon intensity of less than 0.4 t CCWMWhr.
- the electricity has a carbon intensity of less than 0.3 t CCWMWhr.
- the electricity has a carbon intensity of less than 0.2 t CCWMWhr.
- the electricity has a carbon intensity of less than 0.1 t CCWMWhr.
- Compressed water vapour may be used to fluidise solids in one or more of the drying zone, the dehydrating zone or the calcining zone.
- the method comprises the additional step of: recovering heat from the calcined alumina in a first stage heat recovery zone.
- the heat recovered from the calcined alumina may be utilised in the refinery.
- the heat recovered from the calcined alumina is used to heat a liquid or solid heat transfer material.
- the liquid heat transfer material is provided in the form of a high temperature oil. Suitable high temperature oils include Dowtherm.
- heat may be transferred through solid walls or pipes made of steel or other suitable heat transfer solids. The heat transfer material may be utilised in the step of drying the hydrated alumina.
- the heat recovered from the calcined alumina may be used to heat a heat transfer fluid such as a molten salt.
- the heat transfer fluid may be utilised in the step of dehydrating the hydrated alumina.
- the method comprises the additional step of: recovering heat from the calcined alumina in a second stage heat recovery zone.
- the first stage heat recovery zone precedes the second stage heat recovery zone.
- the first stage heat recovery zone is hotter than the second stage heat recovery zone.
- the heat recovered from the calcined alumina may be utilised in the refinery.
- the heat recovered from the calcined alumina is used to heat a heat transfer fluid such as water.
- a heat transfer fluid such as water.
- the water may be flashed to generate water vapour. Said water vapour may be utilised in the refinery where appropriate.
- a system for calcination of hydrated alumina comprising: dehydrating means to reduce the water content of the hydrated alumina and provide partially calcined alumina; and calcining means to heat the partially calcined alumina and provide alumina, wherein the dehydrating means uses at least in part, stored thermal energy, electrical energy, renewable energy or nuclear energy including combinations thereof; the calcining means uses at least in part, electrical energy or combustion energy including combinations thereof; and wherein the stored thermal energy is provided by a thermal material and the thermal material is retained in a retaining system prior to heating the hydrated alumina.
- the retaining system may be provided in the form of one or more storage vessels.
- the dehydrating means is provided in the form of a heat exchanger such as a shell and tube heat exchanger.
- the calcining means is provided in the form of an electric calciner.
- the system further comprises a drying means to reduce the water content of hydrated alumina.
- the drying means may be provided in the form of a cyclone.
- the system further comprises a high temperature heat exchanger to recover heat from the alumina formed in the calciner.
- the high temperature heat exchanger is provided in the form of a plurality of cyclones.
- the system further comprises a low temperature heat exchanger to recover heat from the alumina from the high temperature heat exchanger.
- Figure 1 is a schematic flow sheet showing how a method in accordance with an embodiment of the present invention may be utilised
- Figure 2 is a schematic flow sheet showing how a method in accordance with an embodiment of the present invention may be utilised
- Figure 3 is a schematic flow sheet showing how a method in accordance with an embodiment of the present invention may be utilised
- Figure 4 is a schematic flow sheet showing how a method in accordance with an embodiment of the present invention may be utilised
- Figure 5 is a schematic flow sheet showing how a method in accordance with an embodiment of the present invention may be utilised
- Figure 6 is a schematic flow sheet showing how a method in accordance with an embodiment of the present invention may be utilised
- Figure 7 is a schematic flow sheet showing how a method in accordance with an embodiment of the present invention may be utilised.
- Figure 8 is a schematic flow sheet showing how a method in accordance with an embodiment of the present invention may be utilised.
- Figure 1 shows a schematic flow sheet of the Bayer process circuit 10 for a refinery using a single digestion circuit comprising the steps of: digestion 12 of bauxite 14 in a caustic solution; liquid-solid separation 16 of the mixture to residue 18 and liquor 20; hydrated alumina precipitation 24 from the liquor 20; separation of hydrated alumina 24 and liquor 26; and calcination 31 of the hydrated alumina 24 to alumina 30 and water 32.
- hydrated alumina 24 is pressurised up to about 800 kPa gauge in a lock hopper 50 and passed to a drying zone provided in the present embodiment as a pre-heater 52.
- the damp hydrated alumina 24 is heated at about 180-250 °C. At 250 °C, about 25 % of the physically and chemically bound water is removed.
- the dried hydrated alumina 54 is passed to a dehydrating zone provided in the present embodiment as a decomposer 56.
- the energy provided to the dehydrating zone 56 may be provided in a number of ways including stored thermal energy, electrical energy, renewable energy sources or nuclear energy.
- the decomposer 56 is an indirect shell and tube heat exchanger. Holding times will vary but times in the order of 15 minutes are considered appropriate. At temperatures of about 430 °C, about 60 % of the physically and chemically bound water is removed in the dehydrating zone. At temperatures of 500 °C, about 67 % of the physically and chemically bound water is removed.
- the partially calcined alumina 58 is passed to a calcining zone 60 to remove water of crystallisation.
- the energy provided to the calcining zone 60 may be provided in a number of ways such as an electrically heated calciner, or a calciner heated by combustion of hydrogen, natural gas or fuel oils or combinations thereof.
- the calcined alumina 62 is passed to a high temperature heat recovery stage 64, provided in the present embodiment as an indirect heat exchanger such as a shell and tube variety. Calcined alumina 62 enters the heat recovery stage 64 at about 850 °C exits as partially cooled alumina 66 at about 230 °C. [00160] The partially cooled alumina 66 is depressurised in a lock hopper 68 to atmospheric pressure and passed a low temperature heat recovery stage 70, provided in the present embodiment as an indirect heat exchanger such as a shell and tube variety. Partially cooled alumina 66 enters the recovery stage 70 at about 230 °C and exits as cooled alumina 72 at about 90 °C. The final product of cooled, aluminium oxide 72 may be further treated as required.
- Recovered heat 90 from the high temperature heat recovery stage 64 is used to heat a heat transfer fluid, such as steam or synthetic oil such as Dowtherm ® A which in turn, provides heat to the pre-heater 52. Cooled heat transfer fluid 92 from the pre heater 52 is returned to the high temperature heat recovery stage 64 for heating.
- the heat transfer between the pre-heater and the high temperature heat recovery stage 64 is a closed loop with minimal heat loss.
- Recovered heat 100 from the low temperature heat recovery stage 70 may be used in the refinery. In the present embodiment, it is used to heat a water stream which in turn, is used to wash the hydrated alumina on the filter and heat the slurry of hydrated alumina 24 and liquor 26 to separation. Cooled water 102 is returned to the low temperature heat recovery stage 70 for heating. Trim cooling in a cooling tower may be required.
- Water vapour 110 from the pre-heater 52 may be utilised in the refinery. It may be necessary to compress the water vapour 110 before use.
- Water vapour 114 from the decomposer 56 and water vapour 116 the calciner 60 are combined and passed to the pre-heater 52 to heat the hydrated alumina 24.
- water vapour 116 from the calciner may be passed to the decomposer 56.
- hydrated alumina 24 is pressurised up to about 800 kPa gauge in a lock hopper 50 and passed to a drying zone provided in the present embodiment as a pre heater 52.
- the damp hydrated alumina 24 is heated at about 180-250 °C.
- About 25 % of the physically and chemically bound water is removed at 250 °C.
- the dried hydrated alumina 54 is passed to a dehydrating zone provided in the present embodiment as a decomposer 56.
- the decomposer 56 is an indirect shell and tube heat exchanger. Holding times will vary but times in the order of 15 minutes are considered appropriate.
- At temperatures of about 430 °C about 60 % of the water is removed in the dehydrating zone.
- At temperatures of 500 °C about 67 % of the physically and chemically bound water is removed.
- the partially calcined alumina 58 is passed to a calcining zone, provided in the present embodiment as an electrically heated calciner 60 operating at about 850 °C to remove water of crystallisation. Depending on the temperature and residence time, a small amount of the water of crystallisation may not be removed.
- the calcined alumina 62 is passed to a high temperature heat recovery stage 64, provided in the present embodiment as an indirect heat exchanger such as a shell and tube variety. Calcined alumina 62 enters the heat recovery stage 64 at about 850 °C exits as partially cooled alumina 66 at about 230 °C.
- the partially cooled alumina 66 is depressurised in a lock hopper 68 to atmospheric pressure and passed a low temperature heat recovery stage 70, provided in the present embodiment as an indirect heat exchanger such as a shell and tube variety.
- a low temperature heat recovery stage 70 provided in the present embodiment as an indirect heat exchanger such as a shell and tube variety.
- Partially cooled alumina 66 enters the recovery stage 70 at about 230 °C and exits as cooled alumina 72 at about 90 °C.
- the final product of cooled, aluminium oxide 72 may be further treated as required.
- the decomposer 56 is heated with thermally stored energy from a high temperature molten salt storage vessel 82.
- Molten salt 76 exits the vessel 82 at about 530 °C and indirectly heats the hydrated alumina in the decomposer 56.
- Cooled molten salt at about 300 °C 78 is returned to a low temperature molten salt storage vessel 80.
- the method cycles sequentially and continuously through the two operating states, the charging state and the discharging state, alternatively known as the net energy increasing state and the net energy decreasing state respectively.
- the charging state off-peak electricity may be used to heat the molten salt either as it is transferred from the low temperature storage vessel 80 to the high temperature storage vessel 82 or in the high temperature storage vessel 82 itself.
- the thermal material is being continuously cycled through the heat exchanger to heat the hydrated alumina in the decomposer 56.
- the amount of molten salt in the high temperature molten salt storage vessel 82 increases and the amount of molten salt in the low temperature molten salt storage vessel 80 decreases.
- the amount of molten salt in the low temperature molten salt storage vessel 80 increases and the amount of molten salt in the high temperature molten salt storage vessel 82 decreases.
- the volume of the high temperature molten salt storage vessel 82 must be sufficient to retain sufficient hot molten salt for the duration of the discharging state. For example, if local off-peak electricity is available from 10 pm until 6 am, then the charging state may last for about 10 hours and the discharging state may last for about 14 hours. In addition, even during the charging state, hot molten salt is being removed from the high temperature molten salt storage vessel 82.
- off-peak electricity may also be used to directly heat the hydrated alumina during the charging state.
- the method may also utilise a third state, the steady state.
- a small amount of electricity (off-peak or otherwise) may be used to account for the amount of hot molten salt leaving the high temperature molten salt storage vessel 82.
- the steady state may be briefly operated when transitioning from the other two states.
- Recovered heat 90 from the high temperature heat recovery stage 64 is used to heat a heat transfer fluid, such as steam or Dowtherm ® A which in turn, provides heat to the pre-heater 52. Cooled heat transfer fluid 92 from the pre-heater 52 is returned to the high temperature heat recovery stage 64 for heating. The heat transfer between the pre-heater and the high temperature heat recovery stage 64 is a closed loop with minimal heat loss.
- Recovered heat 100 from the low temperature heat recovery stage 70 may be used in the refinery. In the present embodiment, it is used to heat a water stream which in turn, is used to wash the hydrated alumina on the filter 124 and heat the slurry of hydrated alumina 24 and liquor 26 to separation. Cooled water 102 is returned to the low temperature heat recovery stage 70 for heating. Trim cooling in a cooling tower may be required.
- Water vapour 110 from the pre-heater 52 may be utilised in the refinery. It may be necessary to compress the water vapour before use.
- Water vapour 114 from the decomposer 56 and water vapour 116 the calciner 60 are combined and passed to the pre-heater 52 to heat the hydrated alumina 24.
- water vapour 116 from the calciner may be passed to the decomposer 56.
- FIG. 3 depicts box 128 which defines the portion of the system to which the terms the net energy increasing state and the net energy decreasing state refer.
- Energy enters the box 128 in the form of hot hydrated alumina 54 and energy exits the box in the form of partly calcined alumina 58 and steam 114.
- the thermal energy charging state external energy is supplied to the system defined by box 128.
- the system defined by box 128 is in a net energy increasing state.
- the thermal energy discharging state where no or low external energy is supplied, the system defined by box 128 is in a net energy decreasing state.
- the overall energy within the system is substantially constant, barring short term fluctuations due to inherent process instability.
- the hydrated alumina 24 is pressurised in the lock hopper 50 and passed to a cyclone 130 for drying.
- the dried hydrated alumina 132 is passed to the pre-heating zone 52.
- the dried hydrated alumina 54 at about 250 °C is passed to a dehydrating zone provided as a decomposer 56.
- the partially calcined alumina 58 at about 430 - 500 °C is passed to a calcining zone provided as an electrically heated calciner 60.
- the calcined alumina 62 at about 850 °C is passed to a high temperature heat recovery stage 64.
- the partially cooled alumina 66 is depressurised in a lock hopper 68 and passed a low temperature heat recovery stage 70.
- the final product of cooled, aluminium oxide 72 may be further treated as required.
- Recovered heat 100 from the low temperature heat recovery stage 70 is used to heat a water stream which in turn, is flashed in a bank of one or more flash tanks (only two shown) 140, 142.
- a portion of the heated water 144 may bypass the flash tanks and be used to directly wash the hydrated alumina cake on the filter.
- Water vapour 146 from the flash tank 140 may be used to wash the hydrated alumina cake on the filter 124.
- Water vapour 148 from the final flash tank 142 may be passed through a bank (only one shown) of mechanical vapour recompressors 150 to increase its pressure to just above atmospheric pressure and used to heat the slurry of hydrated alumina 24 and liquor 26 on the filter 124.
- Cooled water 102 is returned to the low temperature heat recovery stage 70 for heating. A portion of the cooled water may be passed to a trim cooling circuit 152 prior to returning to the low temperature heat recovery stage 70.
- Water vapour 110 from the pre-heater 52, water vapour 114 from the decomposer 56, water vapour 116 from the calciner 60 and water vapour 140 from the high temperature heat recovery stage 64 may be combined and mixed with the hydrated alumina 24 entering the cyclone 130.
- At least a portion 153 of the water vapour from the calciner 60 may be returned to the refinery.
- At least a portion of the water vapour 134 from the cyclone 130 may be returned to the refinery. Alternatively, or in addition thereto, at least a portion of the water vapour 134 from the cyclone 130 is passed through a bank (one being shown) of mechanical vapour recompressors 156 and used to fluidise the material in any or all of the pre-heater 52 the decomposer 56, the calciner 60 and the high temperature heat recovery stage 64. It will be appreciated that the water vapour should be compressed and be above its condensing temperature.
- the hydrated alumina 24 is pressurised in the lock hopper 50 and passed to a first cyclone 130 for drying and a second cyclone 150 for further drying and heat recovery.
- the dried hydrated alumina 132 at about 250 °C is passed to a dehydrating zone provided as a decomposer 56.
- the partially calcined alumina 58 at about 430 - 500 °C is passed to a calcining zone provided as an electrically heated calciner 60.
- the calcined alumina 62 at about 850 °C is passed to a high temperature heat recovery stage 64 provided as a series of cyclones 174, 172, 164.
- the partially cooled alumina 66 is depressurised in a lock hopper 68 and passed a low temperature heat recovery stage 70.
- the final product of cooled, aluminium oxide 72 may be further treated as required.
- Recovered heat from the low temperature heat recovery stage 70 is used to heat a water stream 100 which in turn, is flashed in a bank (only two shown) of flash tanks 140, 142.
- a portion of the heated water 144 may bypass the flash tanks and used to directly heat the slurry 124 of hydrated alumina 24 and liquor 26.
- Water vapour 146 from the flash tanks may be used to heat the slurry 124 of hydrated alumina 24 and liquor 26.
- Water vapour 148 from the final flash tank 142 may be passed through a bank (only one shown) of mechanical vapour recompressors 150 to increase its pressure to just above atmospheric pressure and used to heat the slurry 124 of hydrated alumina 24 and liquor 26.
- Cooled water 102 is returned to the low temperature heat recovery stage 70 for heating. A portion of the cooled water may be passed to a trim cooling circuit 152 prior to returning to the low temperature heat recovery stage 70
- Water vapour 160 from the first cyclone 130 is passed to the feed of the cyclone 164.
- Water vapour 162 from the second cyclone 150 is used to heat the hydrated alumina 24 before it enters the first cyclone 130.
- Water vapour 114 from the decomposer 56, water vapour 116 from the calciner 60 and water vapour 164 from the cyclone 174 are combined and used to heat the hydrated alumina 166 entering cyclone 150. Part of the water vapour may be split to cyclone 130 to achieve a higher degree of drying in cyclone 130.
- the water vapour 168 from the cyclone 164 may be returned to the refinery. Alternatively, or in addition thereto, water vapour 168 is passed through a bank (one being shown) of mechanical vapour recompressors 136 and used to fluidise material in any or all of the decomposer 56, the calciner 60 and the second cyclone 172. [00195] Water vapour 170 from cyclone 172 is passed to the feed 62 to cyclone 174. Water vapour 176 from cyclone 174 is passed to the feed to cyclone 150. Water vapour from cyclone 150 is passed to the feed of cyclone 130.
- At least a portion of the water vapour 178 from the cyclone 172 may be passed through a bank (one being shown) of mechanical vapour recompressors 179 and used to fluidise material in any or both of the decomposer 56 and the calciner 60.
- At least a portion of the water vapour 180 from the cyclone 150 may be passed through a bank (one being shown) of mechanical vapour recompressors 181 and used to fluidise material in any or both of the decomposer 56 and the calciner 60.
- At least a portion of the water vapour 182 from the cyclone 174 may be passed through a bank (one being shown) of mechanical vapour recompressors 183 and used to fluidise material in any or both of the decomposer 56 and the calciner 60.
- FIG. 6 A fourth embodiment of the present invention is shown in Figure 6.
- the flow sheet in Figure 6 is essentially the same as that shown in Figure 2 apart from being conducted at atmospheric pressure.
- lock hopper 50 and lock hopper 68 are not required.
- Water vapour 110 from the pre-heater 52, water vapour 114 from the decomposer 56 and water vapour 116 the calciner 60 are combined and passed through a bank (one being shown) of mechanical vapour recompressors 180 to compress the steam to refinery pressure requirements prior to being returned to the refinery.
- FIG. 7 A fifth embodiment of the present invention is shown in Figure 7.
- the flow sheet in Figure 7 is essentially the same as that shown in Figure 6.
- At least a portion 188 of recovered heat 90 from the high temperature heat recovery stage 64 may be used to provide steam to the pressure filter 124.
- FIG. 8 A sixth embodiment of the present invention is shown in Figure 8.
- the thermal material is provided in the form of alumina itself.
- the partially calcined alumina 58 at about 430 - 500 °C is passed through a lock hopper 200 to reduce the pressure and passed to the lower temperature storage vessel 202. It is transferred to the higher temperature storage vessel 204 for heating to 650 -1200 °C by off peak electricity or other energy source, including renewable energy to undergo calcination and store thermal energy.
- the calcined alumina is passed to a heat exchanger 206 to heat the molten salt. Molten salt exits 76 the vessel 82 at about 530 °C and indirectly heats the hydrated alumina in the decomposer 56. Cooled molten salt at about 300 °C 78 is returned to the heat exchanger 206.
- electricity may be used to directly heat units 56, 76, 78 and/or 206.
- At least a portion 208 of the cooled calcined alumina from the heat exchanger is passed to the high temperature heat recovery stage 64 for further cooling as described above.
- the method cycles sequentially and continuously through the two operating states, the charging state and the discharging state, alternatively known as the net energy increasing state and the net energy decreasing state respectively.
- the charging state off-peak electricity or renewable sourced energy may be used to heat the partially calcined alumina either as it is transferred from the low temperature storage vessel 202 to the high temperature storage vessel 204 or in the high temperature storage vessel 204 itself.
- the alumina heat transfer material is being continuously cycled through the heat exchanger 206 to heat the molten salt which in turn heats the hydrated alumina in the decomposer 56.
- the volume of the high temperature storage vessel 204 must be sufficient to retain sufficient hot alumina for the duration of the discharging state. For example, if local off-peak electricity is available from 10 pm until 6 am, then the charging state may last for about 10 hours and the discharging state may last for about 14 hours. In addition, even during the charging state, hot alumina is being removed from the high temperature alumina storage vessel 204. [00208] In addition to using off-peak electricity to heat the alumina during the charging state, off-peak electricity may also be used to directly heat the hydrated alumina during the charging state.
- the method may also utilise a third state, the steady state.
- a small amount of electricity (off-peak or otherwise) may be used to account for the amount of hot alumina leaving the high temperature t storage vessel 204.
- the steady state may be briefly operated when transitioning from the other two states.
- Figure 8 depicts box 220 which defines the portion of the system to which the terms the net energy increasing state and the net energy decreasing state refer.
- external energy is supplied to the system defined by box 220.
- the system defined by box 220 is in a net energy increasing state.
- the thermal energy discharging state where no or low external energy is supplied, the system defined by box 220 is in a net energy decreasing state.
- the overall energy within the system is substantially constant, barring short term fluctuations due to inherent process instability.
- a stream of desuperheating water 210 is added to the water vapour 212 from the hot storage vessel 204 and pressurised in a bank of mechanical vapour compressors 214.
- the heated water vapour 216 is mixed with water vapour stream 114 from the decomposer 56.
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- Inorganic Chemistry (AREA)
- Physical Or Chemical Processes And Apparatus (AREA)
- Inorganic Insulating Materials (AREA)
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Abstract
Description
Claims
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AU2022231808A AU2022231808A1 (en) | 2021-03-12 | 2022-03-11 | Method for calcination |
BR112023018375A BR112023018375A2 (en) | 2021-03-12 | 2022-03-11 | CALCINATION METHOD |
CN202280020866.1A CN117177942A (en) | 2021-03-12 | 2022-03-11 | Calcination process |
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AU2021900721A AU2021900721A0 (en) | 2021-03-12 | Method for calcination | |
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AU2021221796A AU2021221796A1 (en) | 2021-03-12 | 2021-08-25 | Method for calcination |
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US11867093B2 (en) | 2020-11-30 | 2024-01-09 | Rondo Energy, Inc. | Thermal energy storage system with radiation cavities |
US11913361B2 (en) | 2020-11-30 | 2024-02-27 | Rondo Energy, Inc. | Energy storage system and alumina calcination applications |
US11913362B2 (en) | 2020-11-30 | 2024-02-27 | Rondo Energy, Inc. | Thermal energy storage system coupled with steam cracking system |
US12018596B2 (en) | 2020-11-30 | 2024-06-25 | Rondo Energy, Inc. | Thermal energy storage system coupled with thermal power cycle systems |
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US5286472A (en) * | 1989-11-27 | 1994-02-15 | Alcan International Limited | High efficiency process for producing high purity alumina |
EP2955372A2 (en) * | 2014-06-11 | 2015-12-16 | Kevin Lee Friesth | Quintuple-effect generation multi-cycle hybrid renewable energy system with integrated energy provisioning, storage facilities and amalgamated control system |
US20190275485A1 (en) * | 2016-10-31 | 2019-09-12 | Calix Ltd | A flash calciner |
-
2022
- 2022-03-11 WO PCT/AU2022/050199 patent/WO2022187903A1/en active Application Filing
- 2022-03-11 BR BR112023018375A patent/BR112023018375A2/en unknown
- 2022-03-11 AU AU2022231808A patent/AU2022231808A1/en active Pending
Patent Citations (3)
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US5286472A (en) * | 1989-11-27 | 1994-02-15 | Alcan International Limited | High efficiency process for producing high purity alumina |
EP2955372A2 (en) * | 2014-06-11 | 2015-12-16 | Kevin Lee Friesth | Quintuple-effect generation multi-cycle hybrid renewable energy system with integrated energy provisioning, storage facilities and amalgamated control system |
US20190275485A1 (en) * | 2016-10-31 | 2019-09-12 | Calix Ltd | A flash calciner |
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Publication number | Priority date | Publication date | Assignee | Title |
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US11867093B2 (en) | 2020-11-30 | 2024-01-09 | Rondo Energy, Inc. | Thermal energy storage system with radiation cavities |
US11867096B2 (en) | 2020-11-30 | 2024-01-09 | Rondo Energy, Inc. | Calcination system with thermal energy storage system |
US11873743B2 (en) | 2020-11-30 | 2024-01-16 | Rondo Energy, Inc. | Methods for material activation with thermal energy storage system |
US11873742B2 (en) | 2020-11-30 | 2024-01-16 | Rondo Energy, Inc. | Thermal energy storage system with deep discharge |
US11913361B2 (en) | 2020-11-30 | 2024-02-27 | Rondo Energy, Inc. | Energy storage system and alumina calcination applications |
US11913362B2 (en) | 2020-11-30 | 2024-02-27 | Rondo Energy, Inc. | Thermal energy storage system coupled with steam cracking system |
US11920501B2 (en) | 2020-11-30 | 2024-03-05 | Rondo Energy, Inc. | Thermal energy storage system with steam generation system including flow control and energy cogeneration |
US12018596B2 (en) | 2020-11-30 | 2024-06-25 | Rondo Energy, Inc. | Thermal energy storage system coupled with thermal power cycle systems |
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BR112023018375A2 (en) | 2023-12-05 |
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