Reducing the energy demand of corn based fuel ethanol through salt extractive distillation enabled by electrodialysis

The thermal energy demand for producing fuel ethanol from the fermentation broth of a contemporary corn-to-fuel ethanol plant in the U.S. is largely satisfied by combustion of fossil fuels, which impacts the possible economical and environmental advantages of bio-ethanol over fossil fuels. To reduce the thermal energy demand for producing fuel ethanol, a process integrating salt extractive distillation – enabled by a new scheme of electrodialysis and spray drying for salt recovery – in the water-ethanol separation train of a contemporary corn-to-fuel ethanol plant is investigated. Process simulation using Aspen Plus® 2006.5, with the ENRTL-RK property method to model the vapor liquid equilibrium of the water-ethanol-salt system, was carried out. The integrated salt extractive distillation process may provide a thermal energy savings of about 30%, when compared with the contemporary process for separating fuel ethanol from the beer column distillate

Equilibrium diagram of the water + K2SO4 or Na2SO4 + 1-propanol or 2-propanol systems at boiling conditions and 101.3 kPa

Thermodynamically consistent phase equilibrium data at 101.3 kPa and boiling conditions were determined for the ternary systems water + Na2SO4 + 1-propanol, water + Na2SO4 + 2-propanol, water + K2SO4 + 1-propanol and water + K2SO4 + 2-propanol. In contrast to the systems with Na2SO4, the salting-out effect of K2SO4 was not sufficient to split the miscible propanol + water mixture into two liquid phases. The UNIQUAC equation extended to electrolytes for the liquid phase activity coefficients was used to predict the phase equilibria of all the systems. The model reproduced the experimental results quite well, except for the ternary system water + K2SO4 + 1-propanol. In this case the model predicted liquid-liquid splitting into two liquid phases, when there is not.We would like to thank the DGICYT of Spain for the financial support of project CTQ2014-59496

Modeling Methods for Hydraulic Fracturing Wastewater Treatment Applications

Modeling of hydraulic fracturing wastewater treatment systems must be very accurate so it can be used for real-time modeling and control of the process. The treatment of hydraulic fracturing wastewater is complex because of the variability of the composition of hydraulic fracturing wastewater. In this work, literature review of hydraulic fracturing wastewater and its existing treatment options is presented to demonstrate the difficulties of treating this type of wastewater, including the presence of azeotropic contaminants that cannot be removed by straightforward distillation. Additionally, modeling of individual water treatment system components, in particular low-pressure Venturi mixing nozzles, was conducted using several modeling methods, including analytical, empirical, and neural network models. Both analytical and empirical models were determined to be insufficiently accurate for wastewater treatment applications despite the empirical models being at least twice as accurate as the analytical model, for this application. To create a more general, computationally efficient, and accurate model, artificial neural networks were implemented. The concept of physics-guided artificial neural networks is introduced and evaluated on three different multi-species mixing applications. It was found that physics-guided artificial neural networks can reduce the error of the model by up to 40% for a given network architecture or can reduce the network architecture, and thus computational intensity, by up to 60% for a given error value, as compared to traditional black box artificial neural networks. In order to train the physics-guided network model, both the analytical and empirical models must be used. Once the physics-guided network model is trained it can be applied to any case within its training range with low error and computational intensity. The now-proven physics-guided network model concept can be applied to full wastewater treatment technologies, with sufficiently low error and computational intensity to be used for real-time modeling, control, and optimization of the system, using critical input parameters identified by literature review of existing treatment options.

Separation of binary homogeneous azeotropic mixtures using pervaporation.

Masters Degree. University of KwaZulu-Natal, Durban.The separation of mixtures containing homogeneous azeotropes is often complex and requires the use of enhanced distillation techniques. This leads to a significant increase in capital and operating costs. The use of membrane separation techniques to separate azeotropic mixtures is favoured over extractive distillation, azeotropic distillation and absorption as this is an effective low energy and low-cost alternative. Pervaporation is a membrane-based separation technique often used in industry to dehydrate alcohol-water azeotropes, to remove water from organic solvents or to remove organics from water. The process requires a liquid feed at a pressure high enough to maintain its phase while being depleted of components contained within the feed to form a liquid retentate. A membrane is typically selective for one component with finite permeability for the remaining components in the feed. A vapour phase must be maintained on the permeate side of the membrane by applying a vacuum downstream thereby creating a pressure gradient. A pervaporation unit generally consists of a series of membrane cells grouped together in modules, and interstage heat is applied to the feed of subsequent modules. This investigation focused on the dehydration of alcohols (ethanol, propan-1-ol and propan-2-ol) using a poly(vinyl alcohol) based membrane. An experimental study on ethanol-water under various operating conditions was performed. The effect of permeate pressure (2‒5 kPa), feed temperature (338.15‒348.15 K) and feed water concentration (1‒5 wt.%) are reported in terms of flux and permeate quality. Results confirmed that pervaporation is a suitable method to break an azeotrope. Due to technical issues encountered with the equipment, the experimental determination of pervaporation performance was not pursued further. This prompted an extensive simulation study whereby semi-empirical models were developed for the alcohol-water systems using Aspen Custom Modeler® before exporting to Aspen Plus® for simulation and optimization. Dehydration of an industrial grade propan-2-ol aqueous solution (85 wt.% propan-2-ol) using pervaporation was then rigorously simulated as the final objective, as this is not explored in detail in the literature. Various interstage heat temperatures (363.15, 368.15, 373.15 K) and module arrangements (3, 5 and 8 cells per module) were considered to produce the required retentate stream of less than 2 wt.% water. A total of nine design cases were developed to meet the industry purification requirements (>98 wt.% propan-2-ol in retentate). An economic evaluation (inclusive of operating, investment, and maintenance cost) of the separation was performed. It was confirmed that a membrane setup of 3 modules with 3 cells per module including interstage heating to 373.15 K presented the lowest. total cost of 174.27 $/t. This arrangement provided the most feasible configuration for propan-2-ol dehydration using a PVA-based membrane and when compared to azeotropic distillation from literature, it was found that a saving of 34% could be achieved using pervaporation, assuming a pre-concentrator cost of 1/3 of the total process costs from the literature studies. The comparative economic analysis performed across various processes was based on the total cost per ton of propan-2-ol product, which served as a standardized cost. Two procedural assumptions were applied; an operational time of 300 days per year and 24 hours a day for an industrial plant, and a production rate of 257.69 kg.h-1 propan-2-ol, as per the optimal design case

Producción de etanol absoluto por destilación extractiva combinada con efecto salino

Se presentan los resultados sobre la destilación extractiva de mezclas etanol-agua con polialcohol PAW y las sales CaCl2 y KCOOCH3 disueltas en él, utilizando una relación volumétrica 1:1 de etanol–agua a polialcohol y una concentración de 0.1 g/mL de sal en el polialcohol. Se encontró que el polialcohol PAW modificó el comportamiento azeotrópico de la mezcla etanol–agua según el tipo de sal usada y que presenta ventajas respecto a otros agentes de separación anteriormente reportados, desde el punto de vista de manipulación, costos y grado de modificación del azeótropo agua-etanol. Se propone un proceso industrial de destilación extractiva con sales disueltas en polialcohol PAW, que podría competir con los métodos tradicionales para producir etanol absoluto; el cual modificaría las volatilidades relativas de la mezcla, mejorando la eficiencia de separación, disminuyendo el consumo de energía, tamaño y costo de equipos, evitando problemas de corrosión y manejo de sólidos frecuentes en otros procesos

Solvent-based approaches to evaluate the ABE extractive fermentation

The reindustrialization of ABE fermentation is hampered by significant production costs, linked to high product inhibition and limited intrinsic yield. The reduction of these costs depends on the effective application of integrated toxic product removal techniques. The evaluation of ABE extractive fermentation with solvents of different nature in terms of extraction capacity or biocompatibility is the main objective of this thesis. Attention is focused on the assessment of the solvent influence, not only on the physical effects but also on the metabolism and microbial population dynamics evolution. A mathematical model based on the evolution of the heterogeneous culture inside the bioreactor was proposed and validated ABE extractive fermentation is techno and economically evaluated on a solvent-based comparative basis. The integration of this process within a LCB biorefinery using a 2G type substrate is also considered

Production of anhydrous ethanol by extractive distillation with salt effect

RESUMEN: Se presentan los resultados sobre la destilación extractiva de mezclas etanol-agua con polialcohol PAW y las sales CaCl2 y KCOOCH3 disueltas en él, utilizando una relación volumétrica 1:1 de etanol–agua a polialcohol y una concentración de 0.1 g/mL de sal en el polialcohol. Se encontró que el polialcohol PAW modificó el comportamiento azeotrópico de la mezcla etanol–agua según el tipo de sal usada y que presenta ventajas respecto a otros agentes de separación anteriormente reportados, desde el punto de vista de manipulación, costos y grado de modificación del azeótropo agua-etanol. Se propone un proceso industrial de destilación extractiva con sales disueltas en polialcohol PAW, que podría competir con los métodos tradicionales para producir etanol absoluto; el cual modificaría las volatilidades relativas de la mezcla, mejorando la eficiencia de separación, disminuyendo el consumo de energía, tamaño y costo de equipos, evitando problemas de corrosión y manejo de sólidos frecuentes en otros procesos.ABSTARCT: The results about extractive distillation of water-ethanol mixtures with PAW polyalcohol containing CaCl2 and KCOOCH3 salts disolved in the polyalcohol, using a unitary volumetric relation waterethanol mixture to polyalcohol and a concentration of 0.1 g/mL of each salt in the polyalcohol are presented. It was found that the polyalcohol PAW modified the water-ethanol azeotropic behavior as a function of the salt used. The PAW polyalcohol showed advantages concerning other separation agents previously used from standpoint of costs and water-ethanol azeotrope modification. A new extractive distillation industrial process using PAW polyalcohol disolved salts is proposed; it would modified the relative volatilities of the mixture, improving separation efficiency, diminishing energy requirements, size and equipment costs, avoiding solids handling and corrosion which are frecuently found in conventional separation processes

Process Design and Economic Evaluation of an Ethanol Production Process by Biomass Gasification

A large number of studies are being conducted on finding eco-friendly substitutes for petroleum-based fuels. Utilizing biomass as an energy source can significantly reduce dependency on petroleum, and the emission of greenhouse gases. Ethanol can be produced by gasification of biomass and then subsequent fermentation of the syngas. The objective of this research is to develop full scale steady-state process models for ethanol production from syngas using a computer aided simulation (ASPEN(TM) Plus software). Simulation results were compared with experimental data obtained from an earlier research project conducted at Oklahoma State University. Sensitivity analyses were performed on major units in the process model to determine the minimum ethanol production cost. An economic comparison was also carried out on two commonly used chemical separation processes (Azeotropic distillation and molecular sieve). The two processes were successfully modeled. These process models show that 99.5 wt% ethanol can be produced using either azeotropic or molecular sieve separation. The simulation results indicate that there is a potential to increase the experimental H2 and CO2 production in the gasifier and higher experimental conversion to ethanol is possible in the syngas fermentation process. The production of high purity ethanol using molecular sieves requires less energy than the azeotropic separation process. This can reduce the operating cost of the process significantly which results in a lower price of the final ethanol product.School of Chemical Engineerin