Setiyo Gunawan, I Gede Wibawa : ESTIMATION OF RATE AND LOCATION OF FROST CO2 FORMATION IN CH4+CO2 SYSTEM IN A FREEZE-OUT HEAT EXCHANGER PRESSURIZED LNG AT 20 BARG OPERATION PRESSURE
Setiyo Gunawan S.T., Ph.D
Prof.Dr.Ir. I Gede Wibawa M.Eng.
The presence of impurities such as carbon dioxide (CO2) in the natural gas can disturb the process cryogenic in the liquefaction of natural gas because CO2 will freeze at low temperatures so that it can disturb the process. Therefore, the CO2 content should be eliminated according to the standard desired properties. Currently, CO2 removal technologies being developed is a Cryogenic Freeze-Out Heat Exchanger Area. This technology is an cryogenic integrated system between the liquifaction and removal of CO2 using a heat exchanger in which the purification of impurities by setting the conditions so that impurities can freeze (frost) by utilizing the thermodynamic properties of mixtures of natural gas. Liquifaction utility can be done efficiently by using reversed-Brayton cycle in which nitrogen used as refrigerant. In this study performed calculations to predict the solid-vapor equilibrium system CH4-CO2 using the Peng-Robinson equation and predicted length of heat exchanger, the rate of freezing solid CO2, CO2 in the location of the freezing heat exchanger, and the condition of CO2 out by using the coupled equation of the mass balance and energy. From the research results to the pressurized LNG phase change from gas directly to solid occurs only at concentrations below 20 mol%. For heat exchanger distance, solid CO2 formation rate, the location of the freezing of CO2 in the heat exchanger, and the final conditions of CO2 concentration in the pressurized LNG is 8.8 m, 2.837810-6 kg/s-m, 2.6 m, dan 0.88 %mol.