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

Abstract

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 °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+N₂ mixture, the effect of pressure on the compressor power consumption increased after 10 °C.