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Dividing-wall column (DWC) is a promising thermally coupled distillation technology for separating multicomponent mixtures. However, the difficulty of controlling vapor split ratio in DWC affects its energy consumption and so limits its wider application in industrial practice. The liquid-only side-stream distillation (LSD) process not only eliminates the vapor split in DWC but also shows comparable economic and thermodynamic efficiency with DWC. This study systematically optimizes and compares the economic performance of DWC and double LSD (DLSD) process for separating ethanol-propanol-butanol ternary mixture, and then analyzes exergy flows in these two processes in detail. Results indicate that TAC of DLSD process is 11.47% lower than that of DWC process, and exergy efficiency of DLSD and DWC processes is 10.81% and 8.57%, respectively. However, both processes exhibit similar exergy destruction in condensers, columns, coolers and reboilers. • Double liquid-only side-stream distillation (DLSD) and dividing-wall column (DWC) are presented and optimized. • Both economic assessment and exergy analysis of DLSD and DWC are carried out. • DLSD has lower annual total cost and higher efficiency than DWC. • DWC and DLSD exhibit similar exergy destruction distributions in columns and heat exchangers. [ABSTRACT FROM AUTHOR]

• ED processes for separating 1,2-dichloroethane and n-hexane mixture were developed. • Two heat pump enhanced ED processes were proposed and optimized. • TAC of the heat pump enhanced ED processes is decreased. • Energy efficiency of the ED processes can be improved by employing HP technology. In the industrial process to synthesize ethylene sulfate, a film-forming electrolyte additive for lithium-ion batteries, a significant amount of liquid mixtures of n -hexane (HE) and 1,2-dichloroethane (DCE) are generated, whose separation is challenging because of the formation of a minimum-boiling azeotrope. Hence, in this study, the conventional ED process for separating the HE/DCE mixtures was firstly investigated. Subsequently, since the temperature difference between the overhead vapor and bottom liquid is large, which is not favorable to the application of the vapor recompression heat pump technology, two bottom flash heat pump (HP) assisted extraction distillation (ED) processes, i.e., the bottom flash HP assisted ED (BFHP-ED) process and the coupled vapor recompression and bottom flash HP assisted ED (VRBFHP-ED) process are proposed and optimized in terms of the minimal total annual cost (TAC). The results show that, the thermodynamic efficiency increases from 7.63% for ED, to 13.76% for BFHP-ED, and 13.16% for VRBFHP-ED processes, while CO 2 emissions of the BFHP-ED and VRBFHP-ED processes can be reduced by 41.05% and 39.19%, respectively. [Display omitted] [ABSTRACT FROM AUTHOR]

• Double liquid-only side-stream distillation (DLSD) for separating ethanol, n -propanol and n -butanol mixture. • Temperature control schemes without composition measurement for DLSD are proposed. • Single temperature control (STC) and temperature difference control (TDC) for DLSD are compared. • TDC with feedforward action has better performance by a factor of 5 or more in total integral absolute error. The investigation of dynamic controllability of double liquid-only side-stream distillation (DLSD) is necessary due to its good potential for separating multicomponent mixtures in industrial practice. However, control strategy for DLSD is unique and complex owing to the existence of liquid side transfer streams. This study proposed three temperature control schemes without composition measurement for DLSD, i.e., single temperature control without feedforward structure (CS1), single temperature control and temperature difference control with feedforward structure (CS2 and CS3). Results demonstrate that DLSD process can be operated smoothly under ±20% feed flow rate and composition disturbances. The use of feedforward structure in CS2 and CS3 eliminates the transient deviations in the responses of product purities in CS1. Overall, CS3 provides better control for DLSD than CS1 and CS2 in terms of lower total sum of integral absolute error (by a factor of nearly 50 and 10, respectively). [ABSTRACT FROM AUTHOR]

Sustainability is an important and difficult consideration for the stakeholders/decision-makers when planning a biofuel supply network. In this paper, a Mixed-Integer Non-linear Programming (MINLP) model was developed with the aim to help the stakeholders/decision-maker to select the most sustainable design. In the proposed model, the emergy sustainability index of the whole biodiesel supply networks in a life cycle perspective is employed as the measure of the sustainability, and multiple feedstocks, multiple transport modes, multiple regions for biodiesel production and multiple distribution centers can be considered. After describing the process and mathematic framework of the model, an illustrative case was studied and demonstrated that the proposed methodology is feasible for finding the most sustainable design and planning of biodiesel supply chains. [ABSTRACT FROM AUTHOR]

• The optimal seed amount for hydrolysis of unenriched TiOSO 4 solution was 1.5 wt%. • The optimal F value for hydrolysis of unenriched TiOSO 4 solution was 1.9. • The optimal aging time for hydrolysis of unenriched TiOSO 4 solution was 35 min. • The optimized TiO 2 pigment has excellent properties of TCS = 1842 and SCX = 2.54. • The cost of TiO 2 pigment using unenriched TiOSO 4 solution can be saved by 5%. For the industrial manufacture of TiO 2 pigments via the sulfate process, the particle size and distribution of H 2 TiO 3 obtained by the thermal hydrolysis of TiOSO 4 directly determine the quality of final TiO 2 pigments. In this study, the extra-adding seeded hydrolysis of TiOSO 4 to H 2 TiO 3 by using the unenriched solution with an equivalent TiO 2 concentration of 160 g/L and Fe/TiO 2 ratio of 0.4 was studied. The effect of the process parameters was investigated to obtain the optimal conditions: seed-added amount = 1.5 wt%, F value = 1.9, and aging time = 35 min, at which, the H 2 TiO 3 particles exhibit the narrowest particle size distribution. Importantly, it was demonstrated that the size of the as-obtained H 2 TiO 3 particles becomes larger at the scenarios of smaller primary crystals due to their severer and stronger agglomeration. Furthermore, TiO 2 pigments prepared from the H 2 TiO 3 particles obtained at the optimal process conditions exhibit the best properties, and their total production cost can be reduced by about 5% by using the unenriched TiOSO 4 solution instead of the enriched solution, which is of great industrial value. [ABSTRACT FROM AUTHOR]