Value Creation of Liquefied Petroleum Gas (LPG)

LPG constitutes a mixture of propane, normal butane and isobutane that are very valuable not just as a source of fuel but also as petrochemical feedstock to produce numerous products such as plastics and synthetic rubbers. Thus, if they are purified or separated, the market value of the constituents is higher as compared to their mixture in LPG. Isobutane especially, has the highest market price among the 3 components in LPG. In spite of the potential value mentioned, to get a high purity of
the individual components, separation process will be required. In this case, separation of mukicomponent will require at least 2 distillation columns. Low relative volatility, in the case for the separation of isobutane and normal butane, will require large number of stages for their separation. As the number of trays for the
column gets bigger, the capital expenditure for thecolumn will increase. Therefore, it is important that the process of purifying is optimally traded off between the
operating costs and capital expenditure. Using Aspen HYSYS simulation software, the base case simulation ofthe plantwassimulated. After identifying potential aspect
that can be manipulated in the processes for optimization, they will besimulated. The
base case results were used as the benchmark for evaluation against the alternative separation process simulations that have been successfully simulated namely,
dividing wall column (DWC) and indirect sequencing. This study has shown that the direct sequence (base case), indirect sequence and DWC produces product value of RM 41 000 to RM 42 000 per hour. Results from this simulation have indicated that, the direct sequence is preferred as its throughput is the highest with 1.267 kg of products purified per kW of energy used as compared to the indirect and DWC case with throughputs of 1.085 and 0.316 of purified constituents per kW of energy consumed. The outcome of this study has been achieved while providing an insight on the preliminary analysis of feasibility of this study of creating added value from LPG.