A multicomponent model system is presented in this work. The basic model system contains ethyl acetate (EtAc), ethanol (EtOH), water (HO), and acetic acid (AA); one case study is extended by ethylene oxide (EO) and monoethylene glycol (MEG). This system is strongly non-ideal. Two homogeneous binary azeotropes (EtOH&#;HO, EtOH&#;EtAc), one heterogeneous binary azeotrope (EtAc&#;HO), and one homogeneous ternary azeotrope (EtAc&#;EtOH&#;HO) are reported in the literature [ 35 36 ] and databases [ 26 ]. Despite acetic acid forming no azeotropic mixture with other participating compounds, it is known for its strong association in the vapor phase and the formation of dimers [ 37 ]. Monoethylene glycol does not form an azeotropic mixture with other mentioned components. Unlike other components, ethylene oxide is a gas at room temperature [ 38 ]. For such a system, the NRTL-HOC thermodynamic model is highly recommended [ 15 28 ] as it is capable of calculating the VLLE (vapor&#;liquid&#;liquid phase equilibria) correctly including two liquid phases, azeotropic mixtures composition, and boing points, dimerization in the vapor phase. All the above-mentioned papers have shown simulation results to be in good agreement with experiment data. Moreover, reliable parameters for the NRTL-HOC model can be obtained from available databases (Aspen Plus [ 26 ], DECHEMA, NIST).
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As it was mentioned, an auxiliary chemical reaction was included to enhance the reactive distillation process in the last case study. This auxiliary reaction was chosen to ensure the removal of the main esterification reaction by-product&#;water. Ethylene oxide (EO) hydration was used, Equation (7). Monoethylene glycol (MEG) is produced as the main product of the auxiliary reaction. Further reactions towards higher glycols (diethylene glycol, triethylene glycol) were omitted because of lower reaction rate and negligible change in the composition of product streams [ 23 41 ]. The auxiliary reaction rate is expressed by Equation (8) [ 23 41 ].
In this work, homogeneous catalysis using sulfuric acid was assumed, Equation (5). The reaction rate ([kmol m]) is expressed by Equation (6), which has been used in works [ 23 40 ]. The reaction occurs in the liquid phase; liquid phase molar concentrations ([kmol m]) are used. The concentration of sulfuric acid catalyst was low [ 15 25 ], so its presence in the phase equilibria calculation was neglected.
Mechanism and reaction kinetics of the esterification reaction of ethanol and acetic acid in the presence of acid catalysts has been studied in many works [ 1 40 ]. Three types of catalysis have been reported: autocatalysis, homogeneous catalysis, and heterogeneous catalysis. The reaction rate is low and achievable conversion is up to 20% at high residence times in the case of autocatalysis reaction [ 39 ]. Strong mineral acids, such as sulfuric acid and hydrochloric acid, are traditionally used as homogeneous catalysts [ 15 ]. High conversion, of up to 65.5%, is achieved in industrial applications using sulfuric acid [ 1 ] in the range from 0.2 to 1.0 volume percent of the reactive mixture [ 15 23 ]. Acidic ion exchange resins in various forms have been used as heterogeneous catalysts to increase conversion (slightly below 70%); however, no solid heterogeneous catalyst has been found to increase the reaction rate in favor of ethyl acetate production better than sulfuric acid [ 15 ]. High reaction rate, high conversion, and a smaller amount of catalyst are preferred from the industrial point of view. In addition, process set-up and equipment design are much easier in the case of homogeneous catalysis. On the other hand, equipment corrosion and catalyst recycling are major drawbacks of homogeneous catalysis with sulfuric acid.
Aspen Plus V10 simulation environment provides several options to compile a process model. In this work, three main types of equipment models were used: chemical reactor, heat exchanger, and distillation column/reactive distillation column.
A chemical reactor is simulated by a model of continuous stirred tank reactor (CSTR) which assumes ideal mixing along with rate-controlled chemical reaction based on known kinetics. The reactor can be operated as an isothermal as well as an adiabatic one. The residence time parameter was used to achieve the desired conversion. Valid phases (liquid, vapor, vapor&#;liquid) for the chemical reaction were specified; in case of esterification (5), the chemical reaction rate is expressed by Equation (6) and takes place only in the liquid phase.
Heat exchangers were simulated by the Heater and HeatX models, respectively. A shortcut set-up was applied to reach the desired stream temperature. Heat integration was applied to improve the optimal process design. The minimum stream temperature difference was set to 10 °C.
N
), reactive zone (NR
), feed stage position (f
), reflux ratio (R
). These parameters can be found in the literature [A Rigorous RadFrac column model was used for RD modeling as well as for conventional distillation. This model allows both EQ and NEQ approaches. Building an NEQ model of reactive separation or separation is not as straightforward as it is in the EQ model. The NEQ model requires much more reliable parameters compared to the EQ model. Consequently, the NEQ model is more difficult to calculate and convergence problems often occur. To improve NEQ model convergence, a good initial guess of stage temperature, liquid phase composition, and vapor phase composition have to be used. For this purpose, the EQ model of each column was made in the first step of the simulation using initial column parameters such as the number of theoretical stages (), reactive zone (), feed stage position (), reflux ratio (). These parameters can be found in the literature [ 5 15 ]. Results of the EQ model simulation provide a very good starting point for building the NEQ model [ 19 27 ]. Another advantage of first building the EQ model is the possibility of faster testing of individual case studies [ 28 ]. When the suitable case study concept is selected, the NEQ model is built based on the EQ model results.
d
), packing height (H
), packing dimensions) were set during the calculation procedure with regard to reasonable column hydraulics, pressure drop, and approach to flood.Rate-based set-up must be enabled in the Aspen Plus [ 26 ] in the NEQ model. Therefore, detailed column internal configuration is required next. A packed column is selected similarly to simulation-experimental works [ 22 28 ]. Mass and heat transfer correlation methods were selected according to the recommendation for the packing type (Rashing Ralu-Ring). Column hydraulics was simulated by Aspen Plus built-in hydraulic function assuming correlation for Rashing Ralu-Ring packing type. Column internal configuration (internal diameter (), packing height (), packing dimensions) were set during the calculation procedure with regard to reasonable column hydraulics, pressure drop, and approach to flood.
NR
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) only, where acetic acid is presented. On the other hand, the hydration reaction (7) is enabled in the whole RD column because ethylene oxide reacts with water whenever they meet in the liquid phase. All the above-mentioned column parameters (N
,NR
,f
,R
,d
,H
&#;) were optimized to meet the design criteria of individual columns as well as of the whole process.In the case of an RD column, the chemical reaction rate is expressed by Equations (6) and (8). A homogeneous catalyst (sulfuric acid) is fed to the column together with acetic acid [ 17 23 ]. The esterification reaction (5) is enabled in the reactive zone () only, where acetic acid is presented. On the other hand, the hydration reaction (7) is enabled in the whole RD column because ethylene oxide reacts with water whenever they meet in the liquid phase. All the above-mentioned column parameters (&#;) were optimized to meet the design criteria of individual columns as well as of the whole process.
Animportant chemical solvent, Ethyl Acetate finds application in a variety of industries, like, coatings, adhesives even inks and pharmaceuticals. In this regard choosing your supplier with prudence is paramount to guaranteeing high-quality products that adhere not only to safety standards but also regulatory demands. The following are some of the key factors you should consider when selecting an Ethyl Acetate supplier:
Evaluate Quality Control & Certifications:
Ensure that potential suppliers maintain meticulous quality control procedures and test each batch, as the Ethyl Acetate production process may introduce impurities when not carefully controlled. Request data sheets documenting parameters such as purity levels, hydrocarbon residues, acidity and water content; these are crucial for your evaluation. ISO or similar certifications, which verify adherence to quality management standards, should be held by suppliers. Ensure you review safety data sheets and confirm that the product meets your application&#;s required specifications.
Assess Reliability & Customer Service:
You should make sure that you secure a supplier of Ethyl Acetate who not only delivers orders punctually but also exhibits exceptional overall customer service. Ascertain the lead times for your potential orders and establish protocols in the event of shipment delays. If possible, visit the supplier&#;s facility personally, this will allow you to assess their professionalism and capabilities directly. It is worth noting that reliable suppliers prioritize customer satisfaction; they firmly stand behind their products.
Review Costs & Fulfillment Capabilities:
When comparing suppliers of Ethyl Acetate, one should balance costs with product quality and reliability standards. You should request quotes for varying order volumes to assess pricing models and potential discounts. Additionally, it is crucial &#; ensuring cost-effectiveness &#; that the supplier can meet your required purchase quantities, align delivery frequency according to need, and offer suitable transportation modes. Do not, however, allow price alone to determine your choice; a product may be cheap, yet utterly pointless when its quality proves subpar.
Thorough diligence across a range of factors is necessary for selecting the ideal Ethyl Acetate supplier. Your investment in carefully evaluating prospective suppliers will yield high-quality products that enhance your industrial processes and applications; all this, while maintaining cost-effectiveness, safety and sustainability. Establishing a partnership with an ethical, customer-focused supplier, like Chemical Iran can potentially confer a competitive advantage upon you.
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