AU2008307020A1 - A method and an apparatus for directly heating slurry - Google Patents
A method and an apparatus for directly heating slurry Download PDFInfo
- Publication number
- AU2008307020A1 AU2008307020A1 AU2008307020A AU2008307020A AU2008307020A1 AU 2008307020 A1 AU2008307020 A1 AU 2008307020A1 AU 2008307020 A AU2008307020 A AU 2008307020A AU 2008307020 A AU2008307020 A AU 2008307020A AU 2008307020 A1 AU2008307020 A1 AU 2008307020A1
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- Australia
- Prior art keywords
- heating
- steam
- direct
- slurry
- pipe
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- 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
- C01F7/04—Preparation of alkali metal aluminates; Aluminium oxide or hydroxide therefrom
- C01F7/06—Preparation of alkali metal aluminates; Aluminium oxide or hydroxide therefrom by treating aluminous minerals or waste-like raw materials with alkali hydroxide, e.g. leaching of bauxite according to the Bayer process
- C01F7/062—Digestion
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- 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
- C01F7/04—Preparation of alkali metal aluminates; Aluminium oxide or hydroxide therefrom
- C01F7/06—Preparation of alkali metal aluminates; Aluminium oxide or hydroxide therefrom by treating aluminous minerals or waste-like raw materials with alkali hydroxide, e.g. leaching of bauxite according to the Bayer process
- C01F7/062—Digestion
- C01F7/064—Apparatus for digestion, e.g. digestor vessels or heat exchangers
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- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Health & Medical Sciences (AREA)
- General Health & Medical Sciences (AREA)
- Nutrition Science (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Geology (AREA)
- Inorganic Chemistry (AREA)
- Paper (AREA)
Description
FPME08140041AU Method and Equipment for Directly Heating Slurry Technical Field 5 The present invention relates to a method and equipment for directly heating slurry, particularly to a method and equipment for directly heating bauxite slurry in digestion autoclaving process during production of alumina. 10 Background Art In the present-day alumina plants, slurry in digestion autoclaving process is generally heated in an indirect heating manner. Condensate after indirect heating by using steam need be re-evaporated by using a means to make full use of steam heat. A digester for indirectly heating 15 the slurry requires special mixing to prevent deposition of solid particles. But as new processes and new technologies develop, slurry is heated in a direct heating manner. Direct heating exhibits total utilization of steam heat, a high heat use efficiency, and a desirable heating effect without influence of scaling of the slurry. Moreover, direct heating does not need 20 a condensate self-evaporating system and direct-heating digesters do not need mixing meanss. Heating medium is generally saturated or overheat steam, e.g., in the process of digesting diaspore in the two-stream method overheat steam is used to directly heat the mixed slurry of the digestion autoclaving process. Since the digesting temperature of diaspore is 25 relatively high generally above 260*C. Steam is used to directly heat at such a high temperature, pressure of steam needs to be at least greater than the saturated steam pressure of sodium aluminate at 260'C. Therefore, how to safely utilize steam under a high pressure at a high temperature, make full use of steam heat and prevent flow of slurry back into a steam 30 boiler and how to ensure bauxite ore at an optimal digesting temperature to make the whole procedure continuous, automatic, secure and stable is an important measure for reducing energy consumption, saving energy,
-I-
raising the operation rate and improving economic benefits. Summary of the Invention To solve the above technical problem, the present invention provides 5 a method and equipment for directly heating slurry in order to directly use steam to heat bauxite slurry to put it at an optimal digesting temperature, and allow the whole process to make full use of steam heat and ensure continuous, automatic, safe and stable operation so as to reduce investment for equipment, reduce energy consumption, save energy, and improve 10 economic benefits. The present invention achieves the above object as follows: a method for directly heating the slurry, comprising the steps of: supplying heated slurry to a direct-heating digester through a slurry pipe, and supplying steam into the direct-heating digester through the steam pipe to mix with 15 the slurry to heat the slurry. The method for directly heating the slurry further comprise the step of: releasing pressure via a safety valve when a pressure in the direct-heating digester exceeds a working pressure and draining the material resulting from the pressure relief to a ditch via a discharge means. 20 The steam first enters a steam buffer and then enters the direct-heating digester. Said steam enters from the bottom of the direct-heating digester. Said steam passes through a check valve before entering the direct-heating digester. 25 Said direct-heating digesters comprise a plurality of direct-heating digesters connected in series, wherein two adjacent stages of direct-heating digesters are connected by a pipeline. The slurry and steam in said direct-heating digester enters a next stage of direct-heating digester by a pipe. 30 A temperature detecting and controlling means is provided between the pipe communicating two adjacent direct-heating digesters and the steam pipe entering the direct-heating digester to detect the temperature in - 2the pipe. When the temperature of the material discharged from the direct-heating digester and running in the pipe is lower than a predetermined value, the amount of steam supplied into the direct-heating 5 digester is increased. When the pressure in the steam buffer exceeds the working pressure, pressure is released via the safety valve, and the steam resulting from the pressure relief is drained to a ditch via the discharge means. A bypass means for reducing vibration of the pipe and steam buffer 10 when the equipment is on is connected in parallel on the steam pipe through which said steam enters the steam buffer. An equipment for directly heating the slurry comprises direct-heating digesters, a slurry pipe supplying the slurry to the direct-heating digesters, and a steam pipe supplying steam to the direct-heating digesters. 15 A safety valve and a discharge means are mounted at the top of the direct-heating digester. Said steam pipe, after being communicated with the steam buffer, is communicated with the direct-heating digester. A safety valve and a discharge means are disposed at the top of said 20 steam buffer. A check valve is provided between the steam buffer and the direct-heating digester. The check valve is disposed at a steam inlet of the direct-heating digester. Said direct-heating digesters are connected in series via a pipe. 25 The pipe between the adjacent direct-heating digesters is communicated with the steam pipe. A temperature detecting and controlling means is provided between the pipe between adjacent direct-heating digesters and the steam pipe. A bypass means is connected to said steam buffer via the steam pipe. 30 A steam trap is disposed on the bottom of the steam buffer. According to the present invention, steam is used to directly heat slurry, whereby steam heat can be completely utilized, rate of use of heat -3can be improved, investment for equipment can be saved and electrical energy for mixing can be saved, and whereby the bauxite ore can be ensured for digestion at an optimal digesting temperature always. Moreover, the whole process is continuous, automatic, safe and stable 5 operation and is of great importance in saving investment, reducing energy consumption, saving energy, improving economic benefits, improving production efficiency, and enhancing automatization level of the whole factory. 10 Brief Description of the Accompanying Drawings Fig.1 is a schematic view of the method and equipment for directly heating slurry according to the present invention. In the figure, the reference numeral 1 designates heated slurry, 2 direct-heating digester, 3 safety valve, 4 discharge means, 5 steam, 6 15 bypass means, 7 steam buffer, 8 check valve, 9 temperature detecting and controlling means, and 10 designates steam trap. Modes for Carrying out the Invention The embodiments of the present invention will be described in detail 20 with reference to the drawings, but the scope of protection of the present invention is not limited by the embodiments. The method for directly heating the slurry according to the present invention comprises the steps of: supplying heated slurry 1 to a first-stage direct-heating digester 2 through a slurry pipeline, and enabling the slurry 25 to flow out of a last-stage direct-heating digester 2; supplying steam 5 to a steam buffer 7 through a steam pipeline and then into direct-heating digesters 2 for mixing with the slurry to heat the slurry, wherein the steam 5 enters the direct-heating digester 2 from the bottom in such a way to function to mix the slurry. A pressure in the direct-heating digester 2 30 exceeds a working pressure, pressure is released via a safety valve 3, and material resulting from the pressure relief is drained to a ditch via a discharge means 4. The slurry and steam in the direct-heating digester 2 -4enters a next direct-heating digester via a pipe. A temperature detecting and controlling means 9 is provided between the pipe communicating two adjacent direct-heating digesters 2 and the steam pipe entering the direct-heating digester 2 to detect the temperature 5 in the pipe. When the temperature of the material discharged from the direct-heating digester and running in the pipe is lower than a predetermined value, the amount of steam supplied into the direct-heating digester will be increased. When the pressure in the steam buffer 7 exceeds the working pressure, 10 pressure will be released via the safety valve 3, and the steam resulting from the pressure relief is drained to a ditch via the discharge means 4. An equipment for directly heating the slurry is constructed as follows: the equipment comprises a plurality of direct-heating digesters 2 connected in series, wherein two adjacent direct-heating digesters 2 are connected 15 together by a heated slurry supply pipe, each direct-heating digester 2 is connected to the steam buffer 7 through a steam supply pipe, the direct-heating digester 2 is connected to the check valve 8 and the temperature detecting and controlling means 9, the pipe between the temperature detecting and controlling means 9 and the direct-heating 20 digester 2 is connected to the steam pipe, a bypass means 6 is connected to the steam buffer 7 via the steam pipe, and the bypass means 6 is used to reduce vibration of the pipe and the steam buffer 7 when the equipment is on. The safety valve 3 is mounted at the top of the direct-heating digester 25 2 and the steam buffer 7, the discharge means 4 is connected to the safety means 3, and the safety valves are connected to the discharge meanss 4 through a material pipe. A steam trap 10 is mounted on a water discharge pipe on the bottom of the steam buffer 7, and water accumulated in operation of the steam buffer 7 is drained into the ditch through the steam 30 trap 10. The check valve 8 is provided between the steam buffer 7 and the direct-heating digester 2 and disposed at a steam inlet of the direct-heating digester 2 to prevent reverse flow of the slurry. -5-
Claims (21)
1. A method for directly heating the slurry, characterized in that the method comprise the steps of: supplying heated slurry to a direct-heating 5 digester through a slurry pipe, and supplying steam into the direct-heating digester through a steam pipe to mix with the slurry to heat the slurry.
2. The method for directly heating the slurry according to claim 1, characterized in that the method for directly heating the slurry further comprise the step of: releasing pressure via a safety valve when a pressure 10 in the direct-heating digester exceeds a working pressure and draining the material resulting from the pressure relief to a ditch via a discharge means.
3. The method for directly heating the slurry according to claim 1, characterized in that the steam first enters a steam buffer and then enters the direct-heating digester. 15
4. The method for directly heating the slurry according to claim 3, characterized in that said steam enters from the bottom of the direct-heating digester.
5. The method for directly heating the slurry according to claim 4, characterized in that said steam passes through a check valve before 20 entering the direct-heating digester.
6. The method for directly heating the slurry according to claim 1, characterized in that said direct-heating digesters comprise a plurality of direct-heating digesters connected in series, wherein two adjacent stages of direct-heating digesters are connected by a pipeline. 25
7. The method for directly heating the slurry according to claim 1, 2, 3, 4 or 5, characterized in that the slurry and steam in said direct-heating digester enters a next stage of direct-heating digester by a pipe.
8. The method for directly heating the slurry according to claim 6, characterized in that a temperature detecting and controlling means is 30 provided between the pipe communicating two adjacent direct-heating digesters and the steam pipe entering the direct-heating digester to detect the temperature in the pipe, in that when the temperature of the material -6- discharged from the direct-heating digester and running in the pipe is lower than a predetermined value, the amount of steam supplied into the direct-heating digester is increased.
9. The method for directly heating the slurry according to claim 3, 5 characterized in that when the pressure in the steam buffer exceeds the working pressure, pressure is released via the safety valve, and the steam resulting from the pressure relief is drained to a ditch via the discharge means.
10. The method for directly heating the slurry according to claim 3, 10 characterized in that a bypass means for reducing vibration of the pipe and steam buffer when the equipment is on is connected in parallel on the steam pipe through which said steam enters the steam buffer.
11. An equipment for directly heating the slurry, characterized in that the equipment comprises direct-heating digesters, a slurry pipe supplying 15 the slurry to the direct-heating digesters, and a steam pipe supplying steam to the direct-heating digesters.
12. The equipment for directly heating the slurry according to claim 11, characterized in that a safety valve and a discharge means are disposed at the top of the direct-heating digester. 20
13. The equipment for directly heating the slurry according to claim 11, characterized in that said steam pipe, after being communicated with the steam buffer, is communicated with the direct-heating digester.
14. The equipment for directly heating the slurry according to claim 13, characterized in that a safety valve and a discharge means are disposed 25 at the top of said steam buffer.
15. The equipment for directly heating the slurry according to claim 13, characterized in that a check valve is provided between the steam buffer and the direct-heating digester.
16. The equipment for directly heating the slurry according to claim 30 15, characterized in that the check valve is disposed at a steam inlet of the direct-heating digester.
17. The equipment for directly heating the slurry according to claim -7- 11, characterized in that said direct-heating digesters are connected in series via a pipe.
18. The equipment for directly heating the slurry according to claim 17, characterized in that the pipe between the adjacent direct-heating 5 digesters is communicated with the steam pipe.
19. The equipment for directly heating the slurry according to claim 18, characterized in that a temperature detecting and controlling means is provided between the pipe between adjacent direct-heating digesters and the steam pipe. 10
20. The equipment for directly heating the slurry according to claim 11, characterized in that a bypass means is connected to said steam buffer 7 via the steam pipe.
21. The equipment for directly heating the slurry according to claim 13, 14, 15 or 20, characterized in that a steam trap is disposed on the 15 bottom of the steam buffer. -8 -
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN200710012998.7 | 2007-09-29 | ||
| CNA2007100129987A CN101398262A (en) | 2007-09-29 | 2007-09-29 | Direct heating method and apparatus for pulp |
| PCT/CN2008/001642 WO2009043231A1 (en) | 2007-09-29 | 2008-09-23 | A method and an apparatus for directly heating slurry |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| AU2008307020A1 true AU2008307020A1 (en) | 2009-04-09 |
| AU2008307020B2 AU2008307020B2 (en) | 2011-10-20 |
Family
ID=40516980
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| AU2008307020A Active AU2008307020B2 (en) | 2007-09-29 | 2008-09-23 | A method and an apparatus for directly heating slurry |
Country Status (3)
| Country | Link |
|---|---|
| CN (1) | CN101398262A (en) |
| AU (1) | AU2008307020B2 (en) |
| WO (1) | WO2009043231A1 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105314663B (en) * | 2015-12-11 | 2017-03-22 | 东北大学设计研究院（有限公司） | Device for recycling red mud disposal backwater in aluminum oxide plant and use method of device |
| CN110817915A (en) * | 2019-11-25 | 2020-02-21 | 沈阳铝镁设计研究院有限公司 | Method and device for reducing steam consumption in alumina production |
| CN111644117A (en) * | 2020-06-15 | 2020-09-11 | 惠安先锋机械有限公司 | Special material dissolving and extracting device for industrial design |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5319199A (en) * | 1976-08-06 | 1978-02-22 | Sumitomo Chem Co Ltd | Extracting method for alumina from alumina-containing ore |
| DE3564300D1 (en) * | 1984-04-02 | 1988-09-15 | Kamyr Inc | Sawdust pumping, and processing |
| US6048458A (en) * | 1995-12-01 | 2000-04-11 | Eastern Power Limited | Apparatus and method for waste recycling and conversion |
| GB9613702D0 (en) * | 1996-06-29 | 1996-08-28 | Coin Controls | Coin dispensing apparatus |
| US5753075A (en) * | 1996-10-25 | 1998-05-19 | Stromberg; C. Bertil | Method and system for feeding comminuted fibrous material |
| CN2652912Y (en) * | 2003-09-26 | 2004-11-03 | 中国铝业股份有限公司 | Three grade self evaporator by bauxite steam direct heating Bayer method digestion |
| CN2844102Y (en) * | 2005-11-28 | 2006-12-06 | 中国铝业股份有限公司 | Steam direct heater of reactive kettle |
-
2007
- 2007-09-29 CN CNA2007100129987A patent/CN101398262A/en active Pending
-
2008
- 2008-09-23 WO PCT/CN2008/001642 patent/WO2009043231A1/en active Application Filing
- 2008-09-23 AU AU2008307020A patent/AU2008307020B2/en active Active
Also Published As
| Publication number | Publication date |
|---|---|
| AU2008307020B2 (en) | 2011-10-20 |
| CN101398262A (en) | 2009-04-01 |
| WO2009043231A1 (en) | 2009-04-09 |
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| Date | Code | Title | Description |
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| FGA | Letters patent sealed or granted (standard patent) |