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In this study, the effect of hydrophilic silica nanoparticles on mass transfer in liquid-liquid extraction process was experimentally investigated using the ternary chemical system toluene-acetic acid-water. In order to examine the dispersed phase drop sizes, single drop experiments with a range of nozzle diameters within 0.1–0.51 cm were carried out. Hydrophilic SiO 2 nanoparticles with different volume concentrations of 0.005–0.1 vol% were added to the continuous phase. The results demonstrated that mass transfer coefficient reduced in presence of hydrophilic SiO 2 nanoparticles and maximum deterioration of 22% was observed using 0.1 vol% silica nanofluid for drops generated by 0.2 and 0.4 cm nozzles. Viscosity increase, steric hindrance of nanoparticles at the liquid-liquid interface, reduction in both free volume of mass transfer path and liquid-liquid contact area because of solid nanoparticles presence are introduced as the main reasons of observed behavior. Moreover, it can be concluded from the experimental results that silica nanoparticles do not significantly influence hydrodynamic parameters of the extraction system. [ABSTRACT FROM AUTHOR]

In this research, the influence of silica nanoparticles on hydrodynamics and mass transfer of a spray liquid–liquid extraction column was studied experimentally. The chemical system of toluene−acetic acid–water was used, and the drops were toluene-based nanofluids containing 0.0005–0.01 vol% silica nanoparticles. In addition to nanoparticles fraction in nanofluids, the effects of dispersed phase drop sizes were evaluated making use of three different distributors with different hole diameters. The experiments were performed at fixed volumetric flow rates of dispersed and continuous phases and mass transfer direction was from dispersed to continuous phase. The results showed that silica nanoparticles have no significant influence on the hydrodynamic parameters, while maximum enhancement of 47% in overall mass transfer coefficient was achieved using 0.001 vol% silica nanoparticles for drops generated by the distributor with the largest hole diameter. At higher and lower nanoparticle concentrations, smaller overall mass transfer coefficient was observed. Brownian motion of nanoparticles and induced microconvection are dominant in low concentrations of nanoparticles resulting in enhanced mass transfer. Nanoparticle aggregation and reduction in free volume because of solid nanoparticles presence can be responsible for deteriorated mass transfer in higher nanoparticle concentrations. [ABSTRACT FROM AUTHOR]

[Display omitted] • The hybrid RDWC and pervaporation has been proposed. • In the pervaporation process, series-parallel arrangement along with recycle streams is used. • Heat integration between PV streams and internal flows of RDWC were investigated. • All process parameters are considered as the optimization variables. A new process configuration consisting of hybrid reactive dividing wall column (RWDC)–pervaporation (PV) (with series–parallel arrangement) with feed splitting and heat integration was proposed to produce ETBE. To evaluate the performance of the proposed method, it should be compared with other ETBE production processes. A total of 12 ETBE production processes were optimized for this purpose. All process parameters were considered optimization variables. TAC was used as objective function, but all processes were also compared in terms of energy consumption. To reduce the energy cost in the PV process, heat integration between the internal RDWC flows and streams entering the PV modules was used to eliminate all heaters in the PV process and also the RDWC condenser. Feed splitting was used to reduce the heat duty of the RDWC reboiler. According to the results, the proposed method reduced the TAC by 59% and 36% respectively compared with the conventional processes and the RDWC. This TAC reduction in the hybrid RDWC–PV process relative to the RDWC can be related to a decrease in the number of trays in the main and prefractionator sections, elimination of the condenser and a significant reduction in the heat duty of the reboiler. [ABSTRACT FROM AUTHOR]

• 93 different processes in the ETBE production have been optimized and compared. • In the pervaporation process, series-parallel arrangement along with recycle streams is used. • Combination of HIDiC, FS, and HI methods was used to reduce the energy consumption. • All process parameters are considered as the optimization variables. A new process configuration consisting of hybrid pervaporation (PV) (with series–parallel arrangement and recycle streams)–distillation column (DC) or reactive distillation (RD) with a hybrid feed splitting-heat integrated distillation column (HIDiC) – heat integration method was proposed to produce ETBE. To evaluate the performance of the proposed method, 92 different processes for producing ETBE by RD columns, pressure swing distillation, PV, liquid–liquid extraction column or their combinations were optimized and compared to the new configuration. The PV modules were placed in four sections: before the column, next to distillate, next to bottom product and next to side stream. All process parameters in DC or RD, PV and heat integration were considered optimization variables, and all variables were simultaneously optimized by a hybrid GA–PSO algorithm. The proposed configuration reduced TAC by at least 30% and a maximum of 62% compared with other process configurations. This can be attributed to the use of PV instead of distillation columns, series–parallel arrangement instead of series and parallel arrangements in the PV process to reduce energy consumption and membrane area and also the use of heat integration between internal DC flows and PV streams to eliminate the need for hot utility. [ABSTRACT FROM AUTHOR]

• Series–parallel arrangement of PV with recycle streams was applied. • Heat integration between PV streams and internal flows of RD column was examined. • All process parameters were considered as optimization variables. Tert–amyl methyl ether (TAME) production process is consisted of a reactor, a reactive distillation (RD) column and the methanol recovery section. The bottom product of the RD column is TAME while the distillate is consisted of the azeotropic mixture of methanol and isopentane (i-pentane) that can be separated by either the pervaporation (PV) membrane or conventional pressure swing distillation (PSD) and extractive distillation (ED) methods. The PV process allows the use of both series and parallel arrangements. The series arrangement has a lower membrane area compared to the parallel arrangement, while the parallel arrangement has a lower energy cost. A series–parallel arrangement with recycle streams was used in the present study to take advantage of both the series and parallel arrangements. The HIDiC method was used for reducing energy consumption in the RD column. Moreover, heat integration between PV streams and internal flows in the RD column was used to reduce PV energy consumption. The number of modules in each row, the recycle stream, the heat exchange ratio between the rectifying and stripping sections in the RD column and the heat exchange ratio between PV streams and internal RD streams were obtained by a hybrid GA–PSO algorithm. Furthermore, all RD and PV parameters were considered optimization variables and most importantly, all process variables were optimized simultaneously. According to the results, the proposed process reduced the total annual cost (TAC) by 52% and led to a 57% energetic gain compared to the conventional hybrid RD–PSD process. The proposed process also reduced TAC by 48% and led to a 40% energetic gain in comparison with the hybrid RD–PV process. This can be related to the reduced membrane area compared to the series and parallel arrangements as well as reduced energy costs of PV heaters through heat integration between PV steams and internal flows of the column. [ABSTRACT FROM AUTHOR]

• Rather than PSD and ED methods, PV was used in methanol recovery section in the TAME process. • Heat integration was conducted by combining R-HIDiC and PV. • All process parameters (especially PV parameters) were considered as optimization parameters. • Heat transfer fraction and number of heat exchangers in R-HIDiC were obtained by the optimization algorithm. The TAME production process involves two main steps. The first step pertains to the reactions that lead to the synthesis of TAME, and the second step to the separation of TAME and recovery of methanol. Part of the TAME reaction and separation is carried out in a reactive distillation (RD) column. The product at the top of the RD column is a methanol- and C 5 -containing azeotropic mixture which can be isolated through pressure swing distillation (PSD) and extractive distillation (ED) methods. In this paper, the mixture was isolated through the pervaporation (PV) process, and all parameters related to RD and PV were considered as optimization variables, in particular the PV-related parameters such as the permeate stream pressure, the number of modules, and the temperature of inflow to each module. All variables were optimized simultaneously. The GA and PSO algorithms were combined to optimize the process and, additionally, total annual cost (TAC) was used as the objective function. The internally heat integrated distillation column (HIDiC) method was used to reduce the RD column energy costs, and the number of heat exchangers between the two rectifying and stripping sections was obtained using the optimization algorithm. The results showed that the hybrid PV/R-HIDiC process with heat integration was the best arrangement, resulting in a TAC reduction of 30% and 40% compared to the hybrid PV/RD process and the hybrid PSD/RD process, respectively. In this case, the number of trays in rectifying and stripping sections is respectively 22 and 6. The number of heat exchangers obtained by R-HIDiC method is 5, the number of PV modules is 11 and permeate pressure equals 18 as the most important parameters obtained from the optimization algorithm. [ABSTRACT FROM AUTHOR]

CO 2 capture from power plant emissions has posed a great challenge in recent decades. The key factor to respond to such a challenge is to develop a separation process consuming less energy, but producing high purity and recovery compared to the available commercial technologies such as amine absorption. Adsorption process is one of the promising leads to achieve this goal. However, it suffers from the large time period required for the regeneration step. One remedy to overcome this problem is employing Rapid Temperature Swing Adsorption (RTSA). In this study, a two dimensional mathematical model of a RTSA process was developed. A sensitivity analysis was also carried out to determine how different transport parameters and simplifying assumptions influence the calculated breakthrough curve. It was concluded that the external and inter-particle mass transfer resistances were negligible. Also, the effects of the key operating variables such as water velocity in the adsorption and desorption steps (0.01–1 m/s), gas velocity (0.5–5 m/s), adsorption time period (40–200 s), adsorption temperature (5–40 °C), desorption temperature (80–120 °C), and hollow fiber thickness (80–680 µm) on RTSA performance were investigated. The RTSA performance was analyzed in terms of recovery, purity, productivity, the amount of separated pure carbon dioxide in 24 h, and specific energy consumption. The following conclusions were drawn for the base-case scenario: (1) the best thickness of the hollow fiber is 260 µm in which purity, recovery, and the amount of separated pure CO 2 are at the maximum values (2) a decrease in adsorption step period time tends to an increase in the productivity and recovery, e.g. the productivity and recovery decrease by half if the adsorption step continues after reaching breakthrough time up to fully saturation state, (3) increasing the gas velocity leads to increasing the productivity and decreasing the recovery with the appropriate value of 2.7 m/s, (4) the water velocity in the adsorption and desorption steps were selected 0.4 m/s, and (5) higher adsorption temperature and desorption temperature resulting in less specific energy consumption. [ABSTRACT FROM AUTHOR]