In this research, firstly, a one-dimensional steady state model for a catalytic fixed bed reactor is presented. All mass transfer, heat transfer and momentum equations are considered in this model, applying appropriate assumptions. The results of modeling predict temperature and concentration changes and also pressure drop along the reactor bed length. By applying the modeling, hydrazine catalytic reactor was designed. The design procedure includes thrust and specific impulse and continues with calculation of the bed diameter. Ammonia dissociation and the mass flux were calculated along the length of the bed. Finally, the reactor was designed and tested. In these tests, the maximum reactor temperature was 650 oC, the ammonia dissociation was 59% and the pressure drop was 1. 3 bar, presenting a good coherency with the modeling data.

This study was carried out for surveying the efficiency of biofilm sequencing batch reactor (SBR) for treatment of wastewater with high organic loading. A cylindrical lab scale biofilm SBR was used in this study. Primary microorganisms for startup of the reactor were obtained from return activated sludge of a municipal waste treatment plant. reactor was feed with synthetic wastewater containing mono ethylene glycol as the main carbon source and NH4Cl and KH2PO4 as nutrients. Following startup and acclimation of microorganisms, organic loading was increased via influent COD concentrations of 500, 1000, 1500 and 2000 mg/L in constant hydraulic retention time. The most removal efficiency of 94% was achieved in influent COD concentration of 100 mg/L. According to data obtained in this work, it can be concluded that biofilm SBR has acceptable efficiency for high strength wastewaters.

Melamine is industrially produced from urea. Therefore the kinetic inspection of the relevant reaction seems to be important to the end of accessing a suitable model and design of the catalyzed bed reactor for synthesizing Melamine. The kinetics of the mentioned reaction has not been found in the literature review. A fixed bed reactor with injection solid urea was constructed to inspect the relevant reaction kinetics. Urea is changed into Melamine, CO2 & NH3 at the presence of silica gel catalyst and the temperature of 400°C. The designed experiments were performed at the temperatures 370, 380 & 390°C based on the catalyst weight varying with the molar flow rate of the entering urea [W/FA0 (kgcat/ (grmole/hr)] An equation pointing out the variance of the vv MJ conversion factor according to the ratio W/FA° was reported which followed the patent: XA=a (W/ FA°)b. Based on the mentioned equations above, at each temperature, the reaction rate conforming the concentration of the outlet urea was reported r¢A =k ( CA). The mean reaction order at these three temperatures equaled to n=0.4.The functionality of k conforming T turned out to be an Arrhenius function (k = k0e – E/RT). The activation Kcal energy and the frequency content are 2.212  kcal/grmol and 75.4 respectively.

In this research, Fischer Tropsch synthesis (FTS) has been modeled in the fixed bed chromatographic reactor for the first time by applying a rather complex dispersed plug flow model for fluid phase and linear driving force (LDF) model for adsorbent. Model equations are dynamic, multi component, non-linear and heterogeneous including reaction and adsorption simultaneously Complex kinetics for FTS and water-gas shift (WGS) reaction and the multi component Langmuir adsorption isotherm is used in the model. A set of partial differential and ordinary differential equations with algebraic equations have been converted into a set of ordinary differential equations by using the orthogonal collocation technique. Then this set of equations has been solved by multi-step methods of Numerical Differentiation Formulae (NDF) or Backward Differentiation Formulae (BDF) Known as the Gear's method Consequently, results for dynamic model and effects of modeling parameters have been analyzed Through this fixed bed chromatographic reactor model, one may develop a suitable configuration of simulated moving bed chromatographic reactors.

In this research, zirconium tetrachloride production is studied as one of the stages of zirconium production. Basically, there are two main methods for producing zirconium tetrachloride from zirconium dioxide: The first and older method used in Iran is the fixed bed process. Despite the advantage of the process and equipment simplicity, this method has a lot of problems, including low efficiency and operator safety problems. In this study, the efficiencies of this method and a newer technique that is fluidized bed reactor were compared. Although the capacity of the reactors are very different, according to that comparison which is based on the unit weight of zirconium production, the result has enough validity. Based on this study, the efficiency of the fluidized bed reactor is 14% higher than that of the fixed bed.

SO2 Emissions from different industrial activities such as, production of electricity in power plants, the metallurgical and cement productions, to name a few, are undesired due to this chemical’s harmful effects. Many processes to reduce sulfur dioxide emissions have been developed. Amongst these processes, direct dry sorbent injection is a relatively simple and low-cost process. In the current study, a CFD investigation of the Direct Sulfation Process is presented. This model accounted for this process to take place in a fixed bed reactor. Effects of important operating conditions including the temperature, concentration and pressure were studied in this work. It was shown that these parameters significantly affected the process. Ultimately, obtained theoretical results were shown to be comparable with experimental data available in the literature. This research provided a complementary theoretical method to the existing experimental technique the former of which might be used for any process optimizations.

Operability analysis as one of the most important bridges between process design and process control helps the process designer to investigate the control issues quite early in the design stage. Recently, Vinson and Georgakis suggested a steady state geometrical operability index as a quantitative measure for assessment of process operability. In this paper, DME fixed-bed reactor is heterogeneously modeled based on mass and energy conservation law at steady state condition. To verify the accuracy of the model, simulation results of the conventional reactor is compared with the available industrial plant data. It is observed that there is a good agreement between the simulation result and the plant data. Then, the steady state operability characteristics of DME reactor have been analyzed by using the framework of Vinson and Georgakis. This paper demonstrates the utility of the approach to industrial chemical reactors. By measuring the operability characteristics of the reactor, the input and output operability index of the process is calculated equal to 43.31% and 57.58% respectively. The results showed the low process ability for creation of desired output by available input.

In this research, modeling, simulation and control of a methanol-to-olefins laboratory fixed-bed reactor with electrical resistance furnace has been investigated in both steady-state and dynamic conditions. The reactor was modeled as a one-dimensional pseudo-homogeneous system. Then, the reactor was simulated at steady-state conditions and the effect of different parameters including inlet flow rate, inlet temperature and electrical resistance temperature on reactor performance was studied. Results showed that the most effective parameter is electrical resistance temperature. Thus, it was selected as manipulating variable for controlling product quality. In the next step, dynamic simulation of the process was performed and the effect of different disturbances on the dynamic behavior of the reactor was assessed. Finally, PID and Neural Network Model Predictive (NNMP) controllers were utilized for process control, and their performances were compared to each other. The response of the control system to different disturbances and set point changes showed that both PID and NNMP control systems can maintain the process at the desired conditions. PID controller had smaller rise time and no offset compared to NNMP controller while NNMP controller had smaller overshoot.

In this study, the conversion of standard synthesis gas to linear hydrocarbons is investigated in a single tube Fischer-Tropsch reactor using computational fluid dynamics. For this, a precise two-dimensional pseudo-homogeneous model includes momentum, mass, and energy conservation equations along with species and reaction kinetics relations was developed and numerically solved by computational codes. The shell and tube reactor was filled with spherical cobalt-based catalysts. The operating condition was as follows: coolant temperature: 555 K, pressure: 17 bar and inlet synthesis gas molar flow rate: 0. 0355gmole/s. The values of carbon monoxide and hydrogen conversions, hydrocarbon productions, pressure drop and fluid temperature on the reactor axis was analyzed. The simulation results were validated by comparison with experimental data. The implemented mathematical model predicted the conversion of carbon monoxide and hydrogen equal to 46% and 49%, respectively that was overpredicted in comparison with experimental ones. In the case of reaction products, maximum error was occurred in the propane production rate, 14%, which indicates a good agreement between mathematical results and experimental data.

Ethyl benzene used increasingly each year is the raw material of producing styrene monomer. This substance is produced from benzene alkylation with ethylene or ethanol, depending on the availability and cost of raw materials. In this study benzene alkylation in the presence of ethanol in a catalytic fixed bed reactor in three states of isotherm, adiabatic and non-isotherm-non-adiabatic is mathematically modeled with one dimensional pseudo- homogeneous model; and then has been programmed with math lab software. The reaction kinetics model is used in this study which comes from the experimental equations found by Mr.U.S Ridevi et al. in a zeolite catalyst impregnated with AlCl3 obtained in isotherm mode. The results of this simulation in isotherm state are comparable with experimental data. The adiabatic and non-isotherm-nonadiabatic states also show acceptable results. Furthermore, in this study the effect of various factors such as the feed flow rate, substrate temperature, substrate density, fixed and variable heat capacity and viscosity of fluid has been investigated.