ANALISIS TEKNO EKONOMI PEMANFAATAN POTENSI SUPERKRITIKAL PADA PRODUKSI GAS NATUNA DENGAN LAJU DAN KANDUNGAN CO2 SANGAT TINGGI

• Main Author: Saripudin
• Format: Dissertations
• Language: Indonesia
• Subjects: Pertambangan dan operasi berkaitan
• Online Access: https://digilib.itb.ac.id/gdl/view/81563
• Institution: Institut Teknologi Bandung

A novel method was applied to overcome the carbon dioxide separation from high flow rate CO2 rich natural gas using two approaches. The first approach is utilizing supercritical natural gas to enhance the efficiency of the purification process and the second is using seawater for the pre-cooling process. Several industries have used various CO2 separation methods including membran technology, cryogenic distillation, Controlled Freeze Zone (CFZ) and the Joule-Thomson expansion sistem. Meanwhile, several previous research still studied partial CO2 separation regarding cryogenic separation, gas expansion, and supercritical expansion with pure CO2. This research examines supercritical expansion with experiments and simulations, calculating expansion coefficients, correcting supercritical expansion, and integrating gas production systems to improve previous technology which is still expensive and not yet economical. The cooling and rapid expansion processes were integrated in the CO2 separation from natural gas under supercritical conditions. The experimental apparatus was newly constructed to perform the experiments, and the results were simulated using various equations of state. The experimental setup consists of a CO2 cylinder, CNG vessel, gas mixture vessel equipped with a cooler, phase observation tank, valve, regulator, piping sistem and instrumen equipment for measuring temperatur, pressure and gas flow rate. Furthermore, the experimental results are used in the integration process of natural gas production simulations involving seawater cooling, supercritical expansion and cryogenic fractionation. The experimental result reveals that the cooling temperatur of expansion diminished the outlet temperatur and the gas condensed easily. The result indicated that the natural gas with 45% CO2 expansion from 100 to 16 bar was the most significant CO2 separation at a coolant temperatur of 10oC, resulting in an expansion outlet temperatur of -50oC and a vapor fraction of 0.93. The results of the expansion coefficient of 45% CO2 (100 to 16 bar) with a cooling temperatur of 10-25oC are 6,62 – 7,5 K/Mpa. Acid Gas is the most appropriate property package for predicting the expansion coefficient of CO2-rich natural gas with an Absolute Average Error (AAE) of 4,83%. Meanwhile, the equation with the largest error is EOS van Der Waals with AAE 16,28%. The Joule-Thomson expansion coefficient profile is simulated using MATLAB, resulting in a correction factor of 0,76 – 0,85 being applied to the heat capacity (Cp) value for CO2 concentrations of 25% - 40% mol, whereby the absolute average error tends to zero. For CO2 concentrations of more than 40%, the Joule-Thomson equation cannot be applied because the expansion coefficient exhibits significant errors compared with the experimental data, furthermore the Acid Gas property package became recommended method. The integrated production sistem with a capacity of 600 MMSCFD consisting of subsea pipeline, expansion valve, separator, expansion turbine and cryogenic fractionation produces 143,6 MMSCFD of sweet gas with a purity of 96,55% (CO2<2%-mol). This process also obtains a profit of 20,73 MW from turbine expansion (54,7 to 1,1 bar) and liquid CO2 of 959,6 tons/hour for EOR activities and used as a reactant for petrochemical plants. This study promises that CO2 separation using cooling and expansion methods produces a new approach to improve the weaknesses of CO2 separation with cryogenic systems.