Abstract:
Coal as the enormous reserves of Pakistan should be best utilized as the alternative fuel in the country. The main import of the country is the oil that needs to be abbreviated the dependency. Liquefaction of coal by the indirect method converting first coal into the gaseous product then to valuable oils. The gasifier and FT synthesis technologies pertinent to the liquefaction along with essential streams assembled in aspen plus. The significance of this kind of thesis has really a quizzical repercussion specially energy hungry country like Pakistan.
For this study, Aspen-Plus V8.8 has been utilized to simulate the performance of liquefaction. A moving bed gasifier designed to get some important results using local lignite coal samples, which are helpful in analyzing the potential of this conventional fuel. The gasifier can withstand the temperature of 950°C and a pressure of 3.5MPa. Several numbers of RCSTRs are used to specify gasifier in the model, which utilizes 5 kg/s of coal after drying and pyrolysis. Gaseous product contains CO2 and H2S gases which are removed up to 90% by amine treating to acquire the pure results. Fixed bed reactor under operating conditions of temperature 573K, pressure 17 bars and H/CO ratio 2.1 has high efficiency. The CO conversion and higher hydrocarbons production along the reactor length investigated. Sensitivity analysis and process optimization is done by considering pyrolysis temperature and S/C ratio as input variables. Based on this investigation, critical process steps for process heat integration and syngas yield are identified. Temperature and pressure modification with the length of FT reactor. Mechanism for kinetics of liquefaction is done with the Langmuir Hinshelwood method.
