Physical Modelling of Aluminum Refining Process Conducted in Batch Reactor with Rotary Impeller
Abstract
:1. Introduction
2. Materials and Methods
- The model tank was filled with water up to 0.7 m, and the processing parameters were changed according to Table 2.
- Visualization research was carried out by digital camera, recording the dispersion level for all rotary impellers, whilst changing the processing parameters.
- Next, the tank was saturated with oxygen. The saturation level was measured by two oxygen meters CO-401, Elmetron, Zabrze, Poland (location of oxygen meters is shown in Figure 1b). After reaching the saturation level, argon was introduced into the model by rotary impeller, and processing parameters were according to the variants in Table 2. Removal of oxygen from water, as an analog of hydrogen removal from aluminum [1,22,27], was measured every 0.5 min. The process of aluminum refining in the batch reactor typically lasted 10 min, therefore the process of oxygen removal was carried out for every variant for 10 min.
- Finally, for the selected variants, based on visualization results (dispersion level), RTD curves were measured, the NaCl tracer was poured from the top of the tank with water, the measuring device was switched on, and the three conductometers measured the change in conductivity at three different locations of the reactor model. The obtained results were automatically registered by the computer system.
3. Results and Discussions
3.1. Visualisation Results
3.2. The Research of Oxygen Removal from Water
3.3. Determination of Residence Time Distribution(RTD) Curves
- Impeller A: the worst result (minimum dispersion)—Variant P4 and the best ones P3 and P9.
- Impeller B: the worst result (excessive dispersion)—Variant S9 and the best ones S1 and S6.
- Impeller C: the worst result (minimum dispersion)—Variant R7 and the best ones R6 and R9.
4. Conclusions
- Physical modelling is a helpful method for working out the new design rotary impeller and aids easy identification of the optimal processing parameters.
- The physical model of the refining reactor simulates the conditions prevailing in this reactor during refining process. The rates of gas bubble dispersion significantly influences the efficiency of the hydrogen removal process. Determining the optimal range of gas flow increases the efficiency of the purging process, which in turn reduces its costs.
- The information obtained from the dispersion patterns are dependent on observation and interpretation, and thus improper conclusions can be drawn.
- RTD curves, which are quantitative analysis, provide the information about mixing time of tracer with water, and based on such results the identification of processing parameters, such as flow rate of refining gas and rotary impeller speed, is possible. RTD curves do not give a direct and clear answer, but allow for a satisfactory estimation of the technological parameters and the operation of the reactor.
- Based on research of oxygen removal from water, as an analog of hydrogen desorption from aluminum, the essential information can be obtained about the process and processing parameters, and also about the time of refining.
- The new design impeller B had the best results in all applied methods, the best variants being 8.33 s−1 and 15 L·min−1. The next step of the research should now be to test the new design impeller under industrial conditions.
Author Contributions
Funding
Conflicts of Interest
References
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Characteristic Feature | Value | |||||||||
Volume of the Tank | 230 L | |||||||||
Velocity of Gas Bubble Flow (rotary impeller speed x distance from rotary impeller axis) | Impeller A | Impeller B | Impeller C | |||||||
0.375 m·s−1 | 0.475 m·s−1 | 0.350 m·s−1 | ||||||||
Rotary Impeller Diameter | Impeller A | Impeller B | Impeller C | |||||||
0.15 m | 0.19 m | 0.14 m | ||||||||
Criterial Numbers | ||||||||||
Fluid | water | aluminum | ||||||||
Temperature | 293 K | 973 K | ||||||||
Dynamic Viscosity | 1005 Pa·s | 1000 Pa·s | ||||||||
Surface Tension | 0.072 N·m−1 | 0.868 N·m−1 | ||||||||
Density | 1000 kg·m−3 | 2700 kg·m−3 | ||||||||
Reynold’s Number | Impeller A | Impeller B | Impeller C | Impeller A | Impeller B | Impeller C | ||||
56,250 | 90,250 | 49,000 | 151,875 | 243,675 | 132,300 | |||||
Weber’s Number | 292.97 | 595.40 | 238.19 | 65.61 | 133.35 | 53.35 | ||||
Froude’s Number | 0.095 | 0.121 | 0.089 | 0.095 | 0.121 | 0.089 |
Rotary Impeller A | ||||||||
No. | Impeller Speed, s−1 | Gas Flow Rate, L·min−1 | No. | Impeller Speed, s−1 | Gas Flow Rate, L·min−1 | No. | Impeller Speed, s−1 | Gas Flow Rate, L·min−1 |
P1 | 5.00 (300 rpm) | 10 | P2 | 6.66 (400 rpm) | 10 | P3 | 8.33 (500 rpm) | 10 |
P4 | 15 | P5 | 15 | P6 | 15 | |||
P7 | 20 | P8 | 20 | P9 | 20 | |||
Rotary Impeller B | ||||||||
No. | Impeller Speed, s−1 | Gas Flow Rate, L·min−1 | No. | Impeller Speed, s−1 | Gas Flow Rate, L·min−1 | No. | Impeller Speed, s-1 | Gas Flow Rate, L·min−1 |
S1 | 5.00 | 10 | S2 | 6.66 | 10 | S3 | 8.33 | 10 |
S4 | 15 | S5 | 15 | S6 | 15 | |||
S7 | 20 | S8 | 20 | S9 | 20 | |||
Rotary Impeller C | ||||||||
No. | Impeller Speed, s−1 | Gas Flow Rate, L·min−1 | No. | Impeller Speed, s−1 | Gas Flow Rate, L·min−1 | No. | Impeller Speed, s-1 | Gas Flow Rate, L·min−1 |
R1 | 5.00 | 10 | R2 | 6.66 | 10 | R3 | 8.33 | 10 |
R4 | 15 | R5 | 15 | R6 | 15 | |||
R7 | 20 | R8 | 20 | R9 | 20 |
Flow Rate of Refining Gas, L·min−1 | Type of Dispersion | ||
---|---|---|---|
Rotary Impeller Speed, s−1 | |||
5.00 | 6.66 | 8.33 | |
Impeller A | |||
10 | Minimum | Minimum | Uniform |
15 | Minimum | Minimum | Uniform |
20 | Minimum | Intimate | Uniform |
Impeller B | |||
10 | Intimate | Uniform | Uniform |
15 | Intimate | Uniform | Uniform |
20 | Intimate | Uniform | Excessive uniform |
Impeller C | |||
10 | Minimum | Intimate | Uniform |
15 | Minimum | Intimate | Uniform |
20 | Minimum | Intimate | Uniform |
Type of Rotary Impeller | Variant | Efficiency of Gas Consumption E, ppm/liter |
---|---|---|
Rotary impeller A | P8 | 0.045 |
Rotary impeller B | S7 | 0.065 |
Rotary impeller C | R7 | 0.054 |
Rotary Impeller A | Rotary Impeller B | Rotary Impeller C | |||
---|---|---|---|---|---|
Variants | Time, s | Variants | Time, s | Variants | Time, s |
P1 | 1200 | S1 | 630 | R1 | 1020 |
P2 | 1020 | S2 | 510 | R2 | 780 |
P3 | 810 | S3 | 390 | R3 | 660 |
P4 | 1050 | S4 | 480 | R4 | 930 |
P5 | 870 | S5 | 390 | R5 | 720 |
P6 | 720 | S6 | 300 | R6 | 570 |
P7 | 930 | S7 | 420 | R7 | 1050 |
P8 | 750 | S8 | 360 | R8 | 690 |
P9 | 660 | S9 | 270 | R9 | 540 |
Rotary Impeller A | Rotary Impeller B | Rotary Impeller C | |||
---|---|---|---|---|---|
Variants | Time, s | Variants | Time, s | Variants | Time, s |
P1 | 32 | S1 | 23 | R1 | 35 |
P2 | 35 | S2 | 25 | R2 | 33 |
P3 | 30 | S3 | 28 | R3 | 25 |
P4 | 45 | S4 | 35 | R4 | 32 |
P5 | 40 | S5 | 25 | R5 | 25 |
P6 | 32 | S6 | 18 | R6 | 23 |
P7 | 31 | S7 | 30 | R7 | 30 |
P8 | 30 | S8 | 24 | R8 | 25 |
P9 | 30 | S9 | 23 | R9 | 30 |
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Saternus, M.; Merder, T. Physical Modelling of Aluminum Refining Process Conducted in Batch Reactor with Rotary Impeller. Metals 2018, 8, 726. https://doi.org/10.3390/met8090726
Saternus M, Merder T. Physical Modelling of Aluminum Refining Process Conducted in Batch Reactor with Rotary Impeller. Metals. 2018; 8(9):726. https://doi.org/10.3390/met8090726
Chicago/Turabian StyleSaternus, Mariola, and Tomasz Merder. 2018. "Physical Modelling of Aluminum Refining Process Conducted in Batch Reactor with Rotary Impeller" Metals 8, no. 9: 726. https://doi.org/10.3390/met8090726