| Abstrakt: |
Bio-LNG, also known as liquefied biomethane (LBM) is a highly sustainable version of LNG, with almost the exact same chemical compositions and inherits similar physical and chemical properties. Bio-LNG is increasingly recognized as a sustainable option that can be dropped and blended with LNG, with no changes required onboard the vessel, as fuel for the existing LNG bunkering infrastructure and can be re-gasified and injected in the natural gas pipeline. In order to fulfill the demand of energy, biomethane or also known as renewable natural gas (RNG) need to be transported to the end users. However, transportation in gaseous state is seemed uneconomic especially involving long distances and trans ocean customers. Therefore, liquefaction of biomethane serves an alternative way for the transportation instead of using existing pipeline. Although the processes are extremely energy demanding ones, it is desirable to study the potential of energy-efficiency in the liquefaction processes. This paper aims to develop simulation models of bio-LNG production consisting three main cycles, and to evaluate and compare performances of those three cycles. The liquefaction cycles namely i) Double-mixed Refrigerant (DMR), ii) Propane Pre-cooled Mixed Refrigerant (C3MR) and iii) Cascade. A model of each cycle has been constructed by using ASPEN HYSYS simulator. A published parameters of RNG feed were introduced to each of the cycles. Then, validations against the published results were done and comparative evaluations for the performances focusing on energy consumptions and economics using Aspen Economic Analyzer. For DMR, simulation results show that total energy consumption, total capital cost, operating cost and utilities cost are 968.111 MW, 73,139,000 USD, 19,801,300 USD/year, and 14,263,800 USD/year, respectively. C3MR cycle show 815.7392 MW, 12,908,000 USD, 50,547,500 USD/year and 45,788,500 USD/year, and for cascade cycle, 964.420 MW, 10,575,000, 7,617,130 USD/year, 6,038,230 USD/ year, in that order, value of bio-LNG flowrate for the three cycles at 6239m3/hr, the product production cost for DMR, C3MR and Cascade cycle are 11.72 USD per m3, 2.17 USD per m3, and 1.78 USD per m3. This study demonstrates how energy-efficiency of each cycle influenced the total production cost. [ABSTRACT FROM AUTHOR] |
