Prediction of heat transfer coefficient and compressor power consumption for CO2 with impurities under pipeline transporting condition

摘要

In CCS (carbon capture & storage) process, carbon dioxide is captured with impurities of various componets and different concentration. Under pipeline transporting conditions of near-critical states for CO2, the impurities such as nitrogen, methane, and hydrogen sulfide significantly affect the in-tube heat transfer coefficient and compressor power consumption, which are different from those of the pure carbon dioxide. In the present study, in-tube heat transfer coefficient and compressor power consumption of CO2 with impurities under pipeline transporting of its diameter 600 mm were predicted by using the theoretical models; the Gnielinski correlation and the Darcy-Weisbach equation. Thermal and transport properties were estimated by the Chung model and REFPROP. This prediction of the in-tube heat transfer coefficient was conducted under various parameters; CO2 mole fraction from 0.90 to 1.00 in mixture, pressure from 80 to 120 bar, temperature from -20 to 60 degrees C, and velocity from 1 to 4 m/s. The compressor power consumption was estimated in the pipeline of 100 km. In-tube heat transfer coefficient and compressor power consumption follows the trends of pure CO2, and were decided by the type and quantity of impurity. The maximum heat transfer coefficient of CO2 mixture decreased with increasing pressure in supercritical condition. When CO2 mole fraction was 0.95 in CO2+N-2 mixture, the effect of pressure on the compressor power consumption increased after 10 degrees C.