Simulation of a single-stage evaporator system integrated with a mechanical vapor compressor for concentrating the electrolytic system KNO3 – H2O

A simulation of a single-stage evaporator system integrated with a mechanical compressor for a case study (concentrating the electrolytic system KNO3 – H2O) was performed. A mathematical model of the subsystem of a single-stage evaporator, a mechanical compressor, and superheated steam seeding is presented. Microsoft Excel with VBA (Visual Basic for Application) was used to solve the mathematical model. The model was solved by an iterative method where the values of the in-let stream temperature and the salt concentration in the concentrated stream at the evaporator outlet were assumed. The process parameters of the system have been determined. Since the goal of any industrial process is to minimize costs and maximize products, the impact of mean temperature difference changes on saturation water consumption and molar salt content in the concentrated stream was presented. 106.92 kg/h of freshwater are required to obtain 18% by weight of salt in a concentrated stream, while 432.30 kg/h of fresh water are required to obtain 25% by weight of salt in a concentrated stream. Consumption of heating steam ranged from 1760.31 to 4473.4 kg/h depending on the average temperature difference. By increasing the temperature differences from 10 to 25 ◦C, the amount of transferred upper lines increases from 1025 to 2750 kW, which is an advantage of increasing the mean temperature difference. The disadvantage of the larger temperature difference is the increase in the power of the mechanical compressor from 97.02 to 384.12 kW

Determination and Application of Improved Kinetic Parameters for Simulation of Maleic Anhydride Synthesis in Industrial Fixed-Bed Reactor

The aims of this study were to determine improved kinetic parameters in five kinetic models for oxidation of n-butane into maleic anhydride in an industrial fixed-bed reactor, and to simulate the reactor performance. On the basis of the measured process parameters, inlet and outlet concentrations of n-butane were calculated and then used to fit the kinetic models. The industrial fixed-bed reactor was approximated by 10 continuous stirred tank reactors (CSTR) connected in series. Based on the calculated outlet concentration of n-butane from the industrial reactor, the outlet concentration of n-butane from the penultimate reactor was calculated. Then the concentrations of n-butane were calculated until the inlet concentration of n-butane in the first reactor was obtained. Kinetic parameters were determined by comparing the inlet concentrations of n-butane in the first reactor with the inlet concentration of n-butane obtained on the basis of the measured process parameters ​​in the industrial fixed-bed reactor. Kinetic models with improved kinetic parameters showed better simulation results compared to kinetic models with the existing kinetic parameters. The best agreement of simulation results and measured values was achieved with application of the kinetic model 2 (Equations (2a-c)). The smallest deviations of numerical simulation in comparison with measured values of the outlet pressure of reaction mixture were 0.45, 0.75 and 0.75% for application of the kinetic model 3 (Equations (3a-c)). The percentage deviations of numerical simulation with improved kinetic parameters and the existing kinetic parameters in comparison with measured values of inside reactor temperature were in the range 0.90-5.36% and in the range 4.17-9.78% (kinetic model 2, Equations (2a-c)), respectively. Keywords: kinetic parameters, kinetic models, maleic anhydride, simulation, fixed-bed reacto

Composting kinetics for mixture of poultry manure and wheat straw based on volatile solids content

The aim of this study was to determine the composting kinetics for mixture of poultry manure and wheat straw based on the volatile solids content. Experimental data was fitted with the first-order and the nth-order kinetic model. The nth-order kinetic model showed better prediction performance than the firstorder kinetic model. For the first-order kinetic model, maximum and mean differences between experimental and simulation results for the content of volatile solids were 5.43% and 3.00%, for the first reactor, and 4.68% and 2.12% for the second reactor, respectively, for the nth-order kinetic model, maximum and mean differences were 4.92% and 1.68%, for the first reactor, and 4.09% and 1.42% for the second reactor, respectively. Keywords: Composting kinetics, poultry manure, wheat straw, volatile solids content. DOI: http://dx.doi.org/10.7251/JEPM1709036

Minimization of Utilities Consumption in a Distillation Column with and without Heat Integration for Separation of a Binary System of Acetone-Methanol

U ovom radu razvijeni su matematički modeli za destilacijsku kolonu s toplinskom integracijom i bez toplinske integracije. Simulacija matematičkih modela primijenjena je za određivanje potrošnje energije u destilacijskoj koloni za razdvajanje binarnog sustava acetona i metanola. Predloženi modeli određuju vrijednosti procesnih varijabli s ciljem utvrđivanja minimalne potrošnje pogonskih sredstava. Prikazana je usporedba rezultata toplinski integrirane destilacijske kolone s rezultatima neintegrirane destilacijske kolone. Rezultati su pokazali da se ušteda energije može postići primjenom toplinske integracije. Predloženi modeli mogu se primijeniti za projektiranje novih ili preuređenje postojećih destilacijskih kolona za razdvajanje binarnih smjesa. Ovo djelo je dano na korištenje pod licencom Creative Commons Imenovanje 4.0 međunarodna.In this work, mathematical models for a distillation column with and without heat integration have been developed. Simulation based on the developed mathematical models was used to determine the energy consumption in the distillation column for separation of a binary system of acetone and methanol. The proposed models determine the values of process variables in order to obtain the minimum utilities consumption. The comparison of results of the heat-integrated distillation column with those of the non-integrated distillation column are presented. The results show that energy savings could be achieved using heat integration. The proposed models may be applied to the design of new or redesign of existing distillation columns for separation of binary mixtures. This work is licensed under a Creative Commons Attribution 4.0 International License

Numerical simulation of soda ash drying process in pneumatic drying system with industrial scale

In this paper a mathematical model for the soda ash drying process in a pneumatic dryer was presented. The model presents a macroscopic aspect of the drying process, for a two-phase, gas-solid system. The model is based on mass and heat transfer between the gas phase and the particle, movement of air and particles through the system, and geometric characteristics of the drying system (fan, air heater, pneumatic dryer, and cyclone). The effects of the process parameters, such as airflow, inlet air temperature, and relative humidity, temperature at the inlet of the dryer, etc., have been studied by solving the model. Also, the model was tested for different values of the capacity of wet soda and different values of the operating parameters of the heating medium. The model was implemented in MATLAB and solved with a nonlinear equations solver. Data obtained by the model were compared with industrial pneumatic dryer data for drying wet soda ash particles with good agreement

Application of validated mathematical model of composting process for study the effect of air flow rate on process performance

The objectives of this study were to develop and validate the mathematical model (kinetic and reactor model) of composting process, as well to used validated model in order investigate the effects of the air flow rate on organic matter conversion, carbon dioxide concentration and mixture temperature. The mathematical model incorporated two microbial populations that metabolized composting material which was split into two different fractions according to its degradability (easily-degradable and hardly-degradable). Comparisons of simulation and experimental results for five dynamic state variables demonstrated that the model has very good predictions of the composting process. Simulations with validated model showed that among three dynamic state variables (organic matter conversion, carbon dioxide concentration, mixture temperature), carbon dioxide concentration is the most sensitive while organic matter conversion is the least sensitive to the change of air flow rate. Keywords: air flow rate, composting, kinetic model, reactor model, simulation. DOI: http://dx.doi.org/10.7251/JEPM1709062

Analiza isparavanja i kristalizacije kalijeva nitrata iz vodene otopine u dvostupnjevitom isparivačkom sustavu i vakuumskom kristalizatoru

U ovom radu prikazana je računalna analiza razdvajanja soli iz dvokomponentnog elektrolitskog sustava. Elektrolitski sustav KNO3-H2O primijenjen je kao “case study” za prikazivanje analize procesa isparavanja i kristalizacije. Sljedeći procesi uzeti su u obzir: dvostupnjeviti isparivački sustav i vakuumski kristalizator s adijabatskim hlađenjem. Razvijen je matematički model dvostupnjevitog isparivačkog sustava i vakuumskog kristalizatora. Matematički model sastoji se od algebarskih jednadžbi. Predloženi model razvijen je u programu Microsoft Excel s VBA (Visual Basic for Applications). Razvijeni model omogućava analizu postojećeg ili dizajniranje novog procesa isparavanja i kristalizacije. Razvijeni model može biti primijenjen na bilo koji dvokomponentni elektrolitski sustav, ali zahtijeva unošenje fizikalno-kemijskih svojstava odgovarajućeg elektrolitskog sustava