ASPEN PLUS

Petroleum products play an important role in different sectors of Bangladesh and Eastern Refinery Limited is the most renowned company to refine crude oil to produce different petroleum products. It produces almost 16 different petroleum products such as LPG, Naphtha, Kerosene, Diesel, AGO, Fuel gas. Though refining process consists of a wide variety of units the major part is done in Crude Distillation Unit (CDU). So, Simulation of Crude Distillation Unit of Eastern Refinery Limited Company was carried out using ‘Aspen Plus’ Process Simulator. The aim of the simulation was to compare the theoretical data with the simulated data. Design data have been taken from Eastern Refinery Limited. Aspen Plus model was developed and simulated data was validated. Different distillation curves obtained from the simulator was found similar to the expected.

An absorption column is required to recover acrylic and acetic acid from the gaseous reactor effluent by contacting gas with water. Two incoming streams are handled by the column. The first is the gas stream of 5756,14 kmol/h with 0,078 % (wt./wt.) acrylic acid. It enters at a temperature of 280,50 °C and a pressure of 1,79 bar. The second stream contains processed water available from plant available at 30 °C and 1 bar and it is mixed with 500 ppm of hydroquinone inhibitor. The choice of hydroquinone as an inhibitor for this process was facilitated by its known properties to prevent polymerization of acrylic acid that is susceptible to radical-initiated polymerization (Schork, 2006). The preferred inhibitor dilution range is between 300ppm – 700 ppm (Elder J.E, 2006). The column has two exiting streams, gaseous stream and aqueous liquid stream. The gaseous stream exits at a flowrate of 5782,13 kmol/h with 390,3 ppm (wt./wt.) of acrylic acid and 23.98 ppm (wt./wt.) of acetic acid. It exits at a temperature of 70,13 °C and a pressure of 1 bar. The second exiting stream is the product stream at a total flowrate of 1576, 9 kmol/h. This stream contains 55.2 % (wt./wt.) acrylic acid (main product). It exits at a temperature of 81, 86 °C and a pressure of 1 bar. This stream is cooled to 46.5 °C prior to the LLE unit.
The product specification requires 100 000 tonnes per year of ester grade acrylic acid (minimum purity 94% (wt.) by oxidation of propylene (94% purity on molar basis). This acid product requires approximately 817.33 kmol/h of processed water. The use of packing columns is recommended for diameters less than 0.6 m (Seader, et al., 2011). The obtained diameter was 5,21 m, thus, a packed column couldn’t be chosen. Sieve trays (as opposed to bubble or valve-type trays) were chosen because of their ease of installation and lower cost compared to packed columns. The choice of sieve trays was also facilitated by their well-known design procedures, low fouling tendency and large capacity (Seader, et al., 2011). The design specifies a column with approximately 24.8 m of height, and containing 60 sieve plates. Processed water with 300 ppm of hydroquinone inhibitor is added to tray 1 (the top tray), and recycle stream is added at tray 69, one stage above the base stage. Single pass crossflow-type trays are employed for all the plates. The column operating pressure is 1 bar and the operating temperature range is from 69,85°C to 81.8 °C. A safety factor of 10% was accounted for in the design temperature and pressure. The total weight of a column vessel including the shell weight, plates and insulation is 1096,85 kN which is equivalent to 111847,55 kg. The absorption column and its associated structures (insulation, trays and vessel) are expected to cost in the region of R 8,8 million. Detailed calculations concerning the absorption column design are presented in Appendix F.

A steady state Aspen Plus® simulation is used to propose and analyse a novel indirect gasification model using steam as the gasifying medium. A sensitivity study is carried out by varying the steam-to-coal ratio. Part of the Syngas produced is combusted in the furnace to provide flue gases at high temperature which is then passed through the bayonets to provide reaction heat. RK-Soave method is used for the evaluation of physical properties of mixed conventional components and CISOLID components in the simulation. The feedstock used in the simulation is indigenous Thar coal from Pakistan, where large coal reserves are present. It was found that a lower steam-to-coal ratio increases the heat content of the syngas produced. Also, the carbon conversion undergoes a maximum at the ratio 2.0. As we increase the steam-to-coal ratio, the yields are better but inevitably reduce the quality of syngas produced. Carbon conversions and H2/CO ratios as high as 95.76% and 3.09 respectively were observed with higher steam to carbon ratios. However, lower ratios provide high yields (69.00%) and cold gas efficiencies (54.41%). Based on these results, it can be said that this parameter significantly influences the syngas quality and processing costs and the diversity of trends suggest a more detailed analysis for optimisation of the process.

A step-by–step procedure on the separation of methanol-water mixture has been developed. Application of
ASPEN PLUS Software was utilized. Aspen Plus interface with Thermodynamics Package selection and an
activity coefficient model are incorporated. UNIQUAC is used. Results obtained have shown a simple method
that can be easily used by all chemical engineers at all levels. The developed method can be used for separation
of other mixtures in the separation process industries.
Keywords: UNIQUAC model, separation, simulation, computer package

Eastern Refinery Limited played an important role in producing petroleum products in Bangladesh and  produces almost 16 different petroleum products. Crude Distillation Unit is the energy intensive unit. Simulation of Crude Distillation Unit of Eastern Refinery Limited Company was carried out using Aspen Plus Process Simulator. Various design data have been taken from Eastern Refinery Limited. Aspen Plus model is developed and simulation data is validated. Different distillation curves obtained from the simulator are similar to the expected.

Objectives: Closed-loop identification is reported to provide better results for identification of systems for control applications. This study conducted closed-loop identification on an Aspen Plus® dynamic simulation based on a pilot-plant distillation column to develop discrete-time linear time-invariant models. Methods/Statistical Analysis: Identification data was generated using set-point perturbations in control variables under proportional-integral control. Identified models were compared with a model identified using open-loop data using 20-step ahead predictions. Findings: Results indicate that closed-loop identification provides more precise prediction models than open-loop identification in this case study. 20-step predictions for closed loop models exceeded 90% fit, whereas the open loop model predictions provided a 70% fit and missed the steady-state values. Application/Improvements: Thus closed-loop identification is more appropriate for applications in model-based controllers.

The organic Rankine cycle (ORC) has recently emerged as a practical approach for generating electricity from low-to-high-temperature waste industrial streams. Several ORC-based waste heat utilization plants are already operational; however, improving plant cost-effectiveness and competitiveness is challenging. The use of thermally efficient and cost-competitive working fluids (WFs) improves the overall efficiency and economics of ORC systems. This study evaluates ORC systems, facilitated by biogas combustion flue gases, using n-butanol, i-butanol, and methylcyclohexane, as WFs technically and economically, from a process system engineering perspective. Furthermore, the performance of the aforementioned WFs is compared with that of toluene, a well-known WF, and it is concluded that i-butanol and n-butanol are the most competitive alternatives in terms of work output, exergy efficiency, thermal efficiency, total annual cost, and annual profit. Moreover, the i-butanol and n-butanol-based ORC systems yielded 24.4 and 23.4% more power, respectively, than the toluene-based ORC system; in addition, they exhibited competitive thermal (18.4 and 18.3%, respectively) and exergy efficiencies (38 and 37.7%, respectively). Moreover, economically, i-butanol and n-butanol showed the potential of generating 48.7 and 46% more profit than that of toluene. Therefore, this study concludes that i-butanol and n-butanol are promising WFs for high-temperature ORC systems, and their technical and economic performance compares with that of toluene. The findings of this study will lead to energy efficient ORC systems for generating power.

Di-tert-butyl-peroxide (DTBP) is a clear organic compound and one of the most stable organic peroxides, formed by the linkage of two flanking tert-butyl groups to a peroxide group. A versatile compound, DTBP is used as a radical initiator in polymer chemistry and organic synthesis, and is a cetane improver in diesel fuel, raising its ignition accelerations. It owes a great deal of its usefulness to the nature of its decomposition, or homolysis; it breaks down at temperatures greater than 100 degrees celsius, and because it can decompose both aerobically and anaerobically, it makes for a multifaceted fuel source. The following is a list of some of the many applications of DTBP: • An important initiator for high pressure, high temperature polymerizations of ethylene and halogenated ethylenes. • Cures resins of allyl acetate and allyl phthalate. • Applied in the making of polyketones from carbon and ethylene • Used as a finishing catalyst for polystyrene • Used as a polymerization cata...