Design factors in gas-lift advanced dissolution (GLAD) system for CO 2 sequestration into the ocean

Abstract

A new method for ocean sequestration of low purity CO 2 gas emitted from thermal power plants has been developed. The method utilizes a gas-lift pump system, named gas lift advanced dissolution (GLAD) system, that dissolves the CO 2 (which has been separated from combustion gas) into seawater at a relatively shallow depth of 200– 300 m and then transports CO 2-rich seawater to a depth greater than 1000 m . The CO 2 concentration of seawater after sequestration shall be limited to a certain value (e.g. 3 mol/ m 3 ) so as to minimize the impact on marine life. This paper describes the numerical simulation model of GLAD's two-phase flow with a CO 2 dissolution that was used to determine the optimal specification of the system. This numerical simulation resulted in the following conclusions: 1. The required length for full dissolution in the dissolution pipes is proportional to the diameter of the injection bubble, and increases linearly with the decrease in the purity of CO 2 gas. 2. The allowable injection rate of CO 2 gas, for a marine life, is proportional to the sectional area of dissolution pipe and increases with the increase in impurity (=1−purity) of the CO 2 gas and the diameter of the injection bubble. 3. Analysis of correlations among these factors will enable system optimization on the total cost basis including the costs for CO 2 separation from exhaust gas, transportation of CO 2 gas to the GLAD site and CO 2 sequestration.