Causticizing tank multi-section heating control method
By using a multi-stage heating unit group and direct steam heating method in a caustic tank with a height of more than 8m, the problem of difficulty in heating control when the caustic tank height is greater than 8m is solved, and effective control and harsh temperature are achieved. Improvement of efficiency.
Patent Information
- Application Number
- CN202411618183.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-13
- Publication Date
- 2025-02-14
AI Technical Summary
When the height of the caustic tank is greater than 8m, the existing one-stage heating control method cannot effectively control the temperature required for the caustic reaction, resulting in a reduction in caustic efficiency.
The multi-stage heating unit group is adopted to achieve the caustic temperature by direct steam heating, and the valve opening or closing state is controlled according to the liquid level height of the caustic tank, so as to realize the online or offline mode control of each heating unit.
The caustic temperature of caustic troughs above 8m is effectively controlled, the caustic efficiency is improved, and the application scenarios of new or renovated salt discharge caustic calcification facilities are expanded.
Smart Images
Figure CN119430247A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of alumina production, and in particular relates to a multi-stage heating control method for a causticizing tank. Background Art
[0002] In the process of alumina production, causticization is an important process to maintain the salt balance of the system. The main principle is to add lime milk to sodium carbonate to produce calcium carbonate and sodium hydroxide. The salt removal causticization method is to concentrate the seed denominator to a certain concentration, first separate it by sedimentation, and then filter (or filter press) the obtained sodium carbonate filter cake into hot water to dilute it to a certain concentration, and then send it to the causticization tank for heating, and add lime milk at the same time. After a certain period of heat preservation, the causticization reaction is completed and then the material is discharged. The causticization tank is generally heated directly by steam, and the temperature is controlled between 90℃ and 100℃.
[0003] At present, the height of the causticizing tank used in production is generally less than 8m. The one-stage heating control method of the causticizing tank can meet the production control requirements. However, when the causticizing tank is greater than 8m, due to the influence of the change of the causticizing tank liquid level in production, the one-stage heating control method will not be able to meet the requirements in order to ensure the temperature required for the causticizing reaction.
[0004] In recent years, due to the decline in the grade of bauxite ore year by year, the accumulation of sodium carbonate in the Bayer process system has accelerated. Many alumina plants are in urgent need of solving the salt balance problem of the system. Adding a salt removal and causticizing process is an effective means. If the existing plant is renovated to add salt removal and causticizing facilities, it is bound to face the limitation of the site and use a causticizing tank with a height greater than 8m for heating. At present, China's alumina production capacity has exceeded 100 million tons, and the annual production capacity of a single line of newly built or renovated (expanded) alumina plants is greater than 1 million tons. Therefore, a multi-stage heating control method for a causticizing tank has broad application prospects and huge market potential. Summary of the invention
[0005] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides a multi-stage heating control method for a causticizing tank, which adopts a multi-stage heating unit group to directly heat with steam to reach a certain causticizing temperature, and controls the opening or closing state of the valve according to the liquid level height of the causticizing tank to realize the control of each heating unit in an online or offline mode, thereby realizing effective control of the causticizing temperature of the causticizing tank with a certain height.
[0006] In order to achieve the above object, the main technical solutions adopted by the present invention include: A multi-stage heating control method for a causticizing tank. In the process of salt removal and causticizing, causticizing slurry and lime milk are added to the causticizing tank. A multi-stage heating unit group is vertically arranged from top to bottom in the causticizing tank. The multi-stage heating unit group is arranged from top to bottom into a plurality of heating units. Each heating unit is connected to a steam pipeline through a pipeline. Valves are respectively arranged on the pipelines connecting each heating unit to the steam pipeline to control each heating unit individually. The opening of the heating units of the multi-stage heating unit group corresponds to the liquid level in the causticizing tank. Steam is directly heated to reach the causticizing temperature. The opening or closing state of the valve is controlled according to the liquid level in the causticizing tank, so as to control each heating unit online or offline.
[0007] Furthermore, the multi-stage heating unit group is composed of several independent heating units, each heating unit is provided with a steam inlet and a steam outlet, each heating unit is composed of a pipe and / or a heat exchanger, and each heating unit is connected by welding, threading, or flanges.
[0008] Furthermore, the valve is a manual valve, an electric valve, a pneumatic valve or a hydraulic valve.
[0009] Furthermore, the causticizing tank is in the form of a flat bottom or a conical bottom, adopts a mechanical stirring method, and the height of the straight section of the causticizing tank is greater than 8m.
[0010] Furthermore, the heat source for heating the causticizing tank is steam, the heating method is direct heating, and the steam pressure is 0.2MPa to 0.5Mpa.
[0011] Furthermore, the steam pipeline can be connected to the multi-stage heating unit group from the top or side wall of the causticizing tank.
[0012] Furthermore, during heating, the heating units at positions corresponding to the liquid level in the causticizing tank and the heating units below the liquid level are turned on.
[0013] Furthermore, the height of the straight section of the causticizing tank is evenly divided into a number of height sections, and a heating unit is arranged within the range of each height section.
[0014] The beneficial effects of the present invention are as follows: a multi-stage heating control method for a causticizing tank of the present invention, in the process of salt removal and causticizing, adds causticizing slurry and lime milk in the causticizing tank, directly heats with steam to reach a certain causticizing temperature by adopting a multi-stage heating unit group, and controls the opening or closing state of the valve according to the liquid level height of the causticizing tank to realize the control of each heating unit in an online or offline mode. The present invention realizes the effective control of the causticizing temperature of a causticizing tank with a certain height, and enables the newly built or modified (expanded) salt removal and causticizing facilities to have more application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS
[0015] Figure 1It is a schematic diagram of the sectional heating control method of the causticizing tank of the present invention.
[0016] In the figure: 1 is a causticizing tank, 2 is a multi-stage heating unit group, 3 is a first valve, 4 is a second valve, and 5 is a third valve. DETAILED DESCRIPTION
[0017] In order to better explain the present invention and facilitate understanding, the present invention is described in detail below through specific implementation modes in conjunction with the accompanying drawings.
[0018] The present invention provides a multi-stage heating control method for a causticizing tank, such as Figure 1 As shown, in the process of salt removal and causticizing, causticizing slurry and lime milk are added to the causticizing tank, and a multi-section heating unit group is vertically arranged from top to bottom in the causticizing tank. The multi-section heating unit group is arranged from top to bottom as a plurality of heating units, and the multi-section heating unit group is composed of a plurality of independent heating units, each of which is provided with a steam inlet and a steam outlet, and each of which is composed of a pipeline and / or a heat exchanger, and each of which is connected by welding, threading, or flange. Each heating unit is connected to the steam pipeline through a pipeline, and valves are respectively arranged on the pipelines connected to the steam pipeline of each heating unit to control each heating unit separately, and the valves are manual valves, electric valves, pneumatic valves, or hydraulic valves. Specifically, during heating, the heating unit at the position corresponding to the liquid level height in the causticizing tank and the heating unit below the liquid level are turned on. More specifically, the height of the straight section of the causticizing tank is evenly divided into a plurality of height sections, and a heating unit is arranged within the range of each height section. The opening of the heating units of the multi-stage heating unit group of the present invention corresponds to the liquid level height in the causticizing tank, steam is used for direct heating to reach the causticizing temperature, the opening or closing state of the valve is controlled according to the liquid level height of the causticizing tank, and each heating unit is controlled online or offline.
[0019] The process system realizes the effective control of the causticizing temperature of the causticizing tank with a certain height, and enables more application scenarios for the newly built or modified (expanded) desalination causticizing facilities.
[0020] The causticizing tank is flat-bottomed or conical-bottomed, and mechanically stirred. The height of the straight section of the causticizing tank is greater than 8m. The heat source for heating the causticizing tank is steam, and the heating method is direct heating. The steam pressure is 0.2MPa to 0.5MPa. The steam pipeline can be connected to the multi-stage heating unit group from the top or side wall of the causticizing tank.
[0021] Example 1 During the salt removal and causticizing process, the causticizing slurry and lime milk of the causticizing tank 1 are added, and the multi-stage heating unit group 2 is used to directly heat with steam to 90°C to 100°C. The vertical section height of the causticizing tank 1 is evenly divided into 3 height sections from top to bottom, and the multi-stage heating unit group 2 is set as 3 heating units according to the 3 divided height sections. Each heating unit is connected to the steam pipeline separately through a pipeline, and the first valve 3, the second valve 4, and the third valve 5 are respectively set on the 3 heating unit connecting pipelines from top to bottom. When the liquid level of the causticizing tank 1 is at a high liquid level, that is, the liquid level of the causticizing tank 1 is within the position range of the first heating unit from top to bottom, the first valve 3, the second valve 4 and the third valve 5 are kept in an open state, so that the three groups of heating units are in an online mode to achieve effective control of the causticizing temperature of the causticizing tank.
[0022] Example 2 Similar to Example 1, the difference is that when the liquid level of the causticizing tank 1 is at the middle liquid level, that is, the liquid level of the causticizing tank 1 is within the position range of the second heating unit from top to bottom, the first valve 3 is closed, and the second valve 4 and the third valve 5 are kept in an open state, so that the first heating unit is in an offline mode, and the second heating unit and the third heating unit are in an online mode, so as to achieve effective control of the causticizing temperature of the causticizing tank.
[0023] Example 3 Similar to Example 1, the difference is that when the liquid level of the causticizing tank 1 is at a low level, that is, the liquid level of the causticizing tank 1 is within the position range of the third heating unit from top to bottom, the first valve 3 and the second valve 4 are closed, and the third valve 5 is kept in an open state, so that the first heating unit and the second heating unit are in an offline mode, and the third heating unit is in an online mode, so as to achieve effective control of the causticizing temperature of the causticizing tank.
[0024] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. Alterations, modifications, substitutions and variations of the above embodiments by a person skilled in the art are all within the scope of the present invention.
Claims
1. A multi-stage heating control method for a causticizing tank, characterized in that: In the process of salt removal and causticizing, causticizing slurry and lime milk are added to the causticizing tank, and a multi-section heating unit group is vertically arranged from top to bottom in the causticizing tank. The multi-section heating unit group is arranged from top to bottom into several sections of heating units, each section of the heating unit is connected to the steam pipeline through a pipeline, and valves are respectively arranged on the pipelines connecting each section of the heating unit and the steam pipeline to control each section of the heating unit separately. The opening of the heating unit of the multi-section heating unit group corresponds to the liquid level height in the causticizing tank, and steam is directly heated to reach the causticizing temperature. The opening or closing state of the valve is controlled according to the liquid level height of the causticizing tank, and each heating unit is controlled online or offline.
2. A multi-stage heating control method for a causticizing tank according to claim 1, characterized in that: The multi-stage heating unit group is composed of several independent heating units, each heating unit is provided with a steam inlet and a steam outlet, each heating unit is composed of a pipeline and / or a heat exchanger, and each heating unit is connected by welding, threading, or flanges.
3. A multi-stage heating control method for a causticizing tank according to claim 1, characterized in that: The valve is a manual valve, an electric valve, a pneumatic valve or a hydraulic valve.
4. A multi-stage heating control method for a causticizing tank according to claim 1, characterized in that: The causticizing tank is in the form of a flat bottom or a conical bottom, and adopts a mechanical stirring method. The height of the straight section of the causticizing tank is greater than 8m.
5. A multi-stage heating control method for a causticizing tank according to claim 1, characterized in that: The heat source for heating the causticizing tank is steam, the heating method is direct heating, and the steam pressure is 0.2MPa-0.5Mpa.
6. A multi-stage heating control method for a causticizing tank according to claim 1, characterized in that: The steam pipeline can be connected to the multi-stage heating unit group from the top or side wall of the causticizing tank.
7. A multi-stage heating control method for a causticizing tank according to claim 1, characterized in that: During heating, the heating units at positions corresponding to the liquid level in the causticizing tank and the heating units below the liquid level are turned on.
8. A multi-stage heating control method for a causticizing tank according to claim 1, characterized in that: The straight section of the causticizing tank is evenly divided into several height sections according to its height, and a heating unit is arranged within each height section.