Computer Aided Design of Fluidized Bed Reactor for the Production of Polypropylene

Fluidized bed reactor (FBR) are the most preferred reaction vessels for reactions involving gas-liquid-solid interaction as they have excellent mass transfer characteristics and exceptional heat distribution system. The fluidized bed consist of two regions: bubble and emulsion phases with an interchange coefficient for transfer of gas between regions. The computation and design of fluidized bed for the production of polypropylene was presented. Three configurations were considered for the plug flow – plug flow configuration, plug flow – mixed flow configuration and mixed flow – mixed flow configuration for the bubble and emulsion phases respectively to investigate the best configuration for highest yield of polypropylene. A computer software (ASPEN HYSIS) was used for the design the three FBR configurations. Results obtained indicated that the plug flow – plug flow configuration produced the highest yield of 51.6mole percent while the plug flow – mixed flow mode had 46.02mole percent and the mixed flow – mixed flow mode produced the lowest yield of 45.19mole percent. However, the mixed flow – mixed flow mode utilized the lowest operating temperature of 194F while the plug flow – mixed flow and plug flow – plug flow modes utilized 202F and 320F respectively, indicating that the mixed flow – mixed flow mode temperature matched plant data for 90oC (194F). The design capacity of the fluidized bed reactor (FBR) is 4813 barrel/day, 4791 barrel/day and 4639barrel/day for PFR/PFR, PFR/CSTR and CSTR/CSTR configurations respectively. Keywords: Fluidized Bed Reactor, Polypropylene, Design, Aspen-Hysis, CSTR, PFR, Operating Temperatur

Computer-Aided Design of a Non-Isothermal Plug Flow Reactor for Non-Catalytic Partial Oxidation of Methane to Synthesis Gas

A computer aided adiabatic, non-isothermal plug flow reactor was designed for the Non-Catalytic Partial Oxidation of methane to Synthesis gas. Design equations for determining the functional dimensions and parameters of the reactor were developed and used to develop the design package for the reactor. The design equations were solved using MathLab and simulated with SimuLink 7.5 to determine optimum values/range of the functional parameters. The optimum values obtained were used to run the design program for a hypothetical reactor processing 600mmscf per day of natural gas. Simulation results showed that the functional parameters: space time and yield of products increases with increase in methane fractional conversion, while space velocity and selectivity decreases. Operating at high pressure (60 -70)bar, increases the selectivity of partial methane oxidation reaction, molar flow rate of synthesis gas (desired product) and space velocity, but decreases space time and reactor length required for high methane fractional conversion  (0.95  - 0.99).  For optimal functional parameters: feed inlet temperature of 1473K (1200oC), reactor diameter of 0.2m, total pressure of 60bar and methane fractional conversion of 0.95; the design program gave the reactor functional dimensions and parameters as:: Reactor volume = 0.1308m3, Reactor length = 9.7734m, Space time = 2.89E-07hr, Space Velocity = 0.2667hr-1, Yield of synthesis gas = 0.8578, Yield of carbon dioxide = 0.0922, Outlet Temperature = 1762.828 K. Keywords: Partial oxidation, Non-catalytic, Methane, Syngas, Reactor desig

Formalization of hydrocarbon conversion scheme of catalytic cracking for mathematical model development

The issue of improving the energy and resource efficiency of advanced petroleum processing can be solved by the development of adequate mathematical model based on physical and chemical regularities of process reactions with a high predictive potential in the advanced petroleum refining. In this work, the development of formalized hydrocarbon conversion scheme of catalytic cracking was performed using thermodynamic parameters of reaction defined by the Density Functional Theory. The list of reaction was compiled according to the results of feedstock structural-group composition definition, which was done by the n-d-m-method, the Hazelvuda method, qualitative composition of feedstock defined by gas chromatography-mass spectrometry and individual composition of catalytic cracking gasoline fraction. Formalized hydrocarbon conversion scheme of catalytic cracking will become the basis for the development of the catalytic cracking kinetic model

Kinetic non-reversibility of the cracking reactions and its accounting during mathematical modeling of industrial process

The paper presents the approach to the catalytic cracking modeling with consideration of the reactions' reversibility/non-reversibility depending on the current concentrations and the cracking temperature. The thermodynamic analysis of the reactions using the quantum-chemical methods allows formulating a hydrocarbons conversion scheme at the thermal equilibrium temperature between the feedstock and the catalyst. The magnitude of the current chemical attraction of reactions is a criterion of thermodynamic non-reversibility of reactions, which is determined at each stage of the calculation. It has been shown that the change in the concentrations of conversion participants and cracking temperature have a significant effect on the catalytic cracking reactions. Thus, the cyclization reactions are non-reversible up to 512.9 °C (A[rij]=6.46 kJ/mol) during the processing of feedstock with saturated hydrocarbons to aromatics ratio is 2.1 and with further temperature increasing the contribution of reverse reactions rises. Also with increasing the saturated hydrocarbons to aromatics ratio from 2.1 to 3.2 in the feedstock, the equilibrium of the reaction shifts to low temperatures from 512.9 to 508.9 °C (A[rij]=6.497 kJ/mol). It is connected with the fact that intensification of the exotermic reactions (alkylation, condensation, coke formation) under certain conditions is possible. It is an important factor in terms of catalyst deactivation and has an effect on the desired product yield

Adsorption of Acetic Acid, Cadmium ions, Lead ions and Iodine Using Activated Carbon from Waste Wood and Rice Husks

This paper presents the performance evaluation of locally prepared activated carbon from rice husk and saw dust. The raw materials were carbonized at different temperatures (600-800°C) using sodium hydroxide (NaOH) as the activating agent. The study includes moisture content determination of the raw materials used in the activation and carbonization processes. The effects of variations in carbonization temperature and concentration of activating agent on various performance indices for good quality absorbent were investigated. The percentage yield of the activated carbon from the raw materials as well as iodine number and adsorption of heavy metals from aqueous solutions were also determined. The experimental data which make a comparative assessment of activated carbon obtained from rice husk and saw dust were also presented. Preliminary examination of the raw materials showed that rice husk and saw dust had a moisture content of 14.6% and 5.8% respectively. Increase in carbonization temperature decreases yield of the active carbon. The highest yield of about 48% was obtained from rice husk at 600°C, with moisture content of 26%. The rice husk at 800°C gave a yield of 47.2% with moisture content of 26.5%. Whilst the yield of the saw dust was 44% at 600°C and 40% at 800°C with moisture content of 17% and 19% respectively. A detailed study of mass transfer processes indicated that activated carbon from these materials show good performance

Six-lump kinetic modelling of adiabatic plug-flow riserreactor in an industrial FCC unit

A six-lump kinetic model is presented that describes the catalytic cracking reactions taking place in an industrial riser-reactor. In this scheme, C3’s (propane and propylene gases) and C4’s (butane and butylenes gases) components of liquefied petroleum gas are predicted independently, as well as gasoline, dry gas, and coke. The riser-reactor is modelled as a plug-flow reactor operating adiabatically. Model-predicted yields of gasoline, C3’s, C4’s, fuel gas, coke, and riser-reactor outlet-temperature, agree reasonably well with plant data obtained from an operating industrial riser-reactor. Sensitivity analysis carried out on the riser-reactor indicates that inlet-temperature of gas-oil (feed), catalystto-gas oil ratio, and mass flowrate of gas-oil, are important process variables that affect the operation of the riser-reactor. It is shown that the minimum catalyst-to-gas oil ratio required for maximum conversion of gas-oil is 3. Simulation results using catalyst-to-gas oil ratio of 6.5, inlettemperature of gas-oil of 505K, and mass flowrate of gas-oil of 67.8 kg/s, give yields of 45.81 % gasoline, 6.32 % C3’s, 10.68 % C4’s, 5.42 % fuel gas, 5.11 % coke, and 26.66 % of unconverted gas-oil