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Salt separation experiments are selectively conducted for the high-salt wastewater of lead-acid batteries. Two useful products, sodium sulfate and sodium chloride, are obtained by evaporation crystallization. The experiment investigates the effect of different temperatures and concentration ratios on the precipitation content and purity of sodium sulfate and sodium chloride during the evaporation and concentration of wastewater, and explores the optimal concentration ratio and temperature for the separation and purification of sodium sulfate. Moreover, the experimental data are fitted with the mathematical model. The results show that for wastewater with 0.5 L chloride ion concentration of 17.9 g/L and sulfate ion concentration of 188.4 g/L, sodium sulfate with 98% purity can be obtained when the concentration ratio is 1.66. When the concentration ratio is in the range of 1.66–2, the precipitation of sodium sulfate is more than 25.76 g in the range of 50 °C–90 °C. When the evaporation temperature is stable at 60 °C and the concentration ratio is from 1.46 to 3.5, both the yield and purity of sodium sulfate crystals are improved, the precipitation of sodium sulfate is up to 88.63 g and the purity is up to 98%.

In recent years, the literature has paid considerable attention to digital twin technology for the implementation of Industry 4.0 and intelligent manufacturing. Most of the literature argues that s...

Complex heat and mass transfer in spray evaporators are areas of intense research due to their increasing predominance in thermal desalination industries. To improve evaporation performance, a cyclone-type spray desalination chamber is developed in this study. Influences of gas-to-liquid volume ratio, temperature and velocity of intake hot air, feeding liquid temperature and nozzle pressure upon evaporation are investigated experimentally and numerically. Thermocouples are used to obtain temperature distribution. Liquid flowmeter and hydrometer are equipped to record evaporation data. Results indicate that swirling flow prolongs the residence time of droplets in the chamber, thus evaporation efficiency can be improved. The rapid development of thermal field is closely related to the two-phase flow and intense phase change heat transfer. Evaporation increases and tends to be stable with gas-liquid ratio, intake air velocity and feeding liquid temperature. Evaporation performance can be improved significantly by increasing temperature of intake hot air. It is highly recommended to control the temperature of feeding liquid and intake air to balance between evaporation performance and energy efficiency. The two-phase flow field can be well organized by matching the spray cone angle and the swirling air flow, thus, a moderate nozzle pressure is suggested to obtain optimal evaporation performance.

This paper focuses on large-scale production release planning problems in wafer fabs. Due to the complexity and dynamic characteristic of production lines, it is useful to develop simulation models to evaluate different production plans and select the optimal one. However, detailed simulation requires large computational costs, especially for large-scale problems. Therefore, we provide a multi-fidelity optimisation with ordinal transformation and optimal sampling (MO2TOS) based on the multiple population evolutionary algorithm to accelerate computational efficiency and address large-scale release planning problems for wafer fabs. In the low-fidelity approximation process of the proposed approach, we employ open queuing theory to estimate cycle times. The experimental results confirm that the low-fidelity model shows a high consistency with the high-fidelity model and the proposed multi-fidelity optimisation method is effective at solving large-scale release planning problems.

In this paper, we study a large-scale re-entrant flexible job shop scheduling problem (FJSP) with the objective of makespan minimization. In the proposed problem, machine quantities, job types, and processes of jobs are known in advance. At least one machine is available for each process. The large production demand for each type of jobs leads to a large-scale manufacture feature in this problem. To address the problem, we first establish a fluid model for the large-scale re-entrant FJSP. Then, we design a priority update rule to improve the assignment of jobs and machines. We finally propose a fast and efficient fluid relaxation algorithm (FRA) to solve the large-scale re-entrant FJSP through the relaxation fluid optimal solution. Numerical results show that the FRA is asymptotically optimal with the increase of the problem scale. The scale of problems has little effect on the FRA’s solving speed. Therefore, we conclude the FRA is suitable for solving the large-scale re-entrant FJSP.

The metastable zone width (MSZW) of Na2SO4-NaCl-H2O from high saline water of lead-acid batteries was studied at different temperatures by the conductivity method in the experiment. Results show that the metastable width of Na2SO4-NaCl-H2O increases with the increase of temperature. The MSZW of Na2SO4-NaCl-H2O containing calcium ion is larger than that of the solution without calcium ion. The MSZW at pH 1 is approximately the same as that at pH 2, and the MSZW is larger than that of the control group. The width of the metastable zone decreases by about 2.5 K from 0 r/min to 100 r/min, and 2.2 K from 100 r/min to 120 r/min. The width of the metastable zone increases to 7.5–8 K when the speed increases from 120 r/min to 140 r/min. The metastable zone width of the solution containing lead is larger than that of the control group, and the difference is in the range of 2.1 ~ 3.9 K.