At this time, thirteen commercial CANSOLV SO2 Scrubbing Systems are in operation and many more are in the detailed engineering or procurement phase. Building on its knowledge of amine based technologies, the CANSOLV SO2 Scrubbing System is a revolutionary regenerable sulfur dioxide (SO2) scrubbing process. This patented technology uses an aqueous amine solution, CANSOLV Absorbent DS, to achieve high selective absorption of sulfur dioxide from a large variety of gas streams. The scrubbing by-product is pure water saturated SO2 gas, recovered by steam stripping which can be converted to sulfuric acid or sulfur. Both the CANSOLV SO2 Scrubbing System and the absorbent have excellent health and safety properties.
The benefits of CANSOLV Absorbent DS™ include:
The CANSOLV SO2 Scrubbing System enables SO2 to be absorbed from the feed gas by counter-current contact with the regenerable amine solvent in the absorption tower. Since the CANSOLV Absorbent DS reacts reversibly with SO2, multi-stage counter-current contacting is used to achieve maximum loading of the SO2 in the regenerable solvent. The solvent is fed to the top of the absorption tower and as it flows down the tower it selectively reacts with SO2 to form an amine-sulfite. At the bottom of the absorption tower, the rich amine is pumped to a regeneration tower where it is heated to reverse the absorption reaction. As the CANSOLV Absorbent DS moves down the regeneration tower, it is gradually stripped of SO2. The lean amine from the bottom of the regeneration tower is returned to the absorption tower for additional SO2 absorption. Sensible heat from the lean amine is used to heat incoming rich amine to maximize heat recovery.
The amount of heat added in the regeneration step will determine the extent to which the CANSOLV Absorbent DS is stripped of SO2 . The more heat is added, the leaner the amine will be at the bottom of the regeneration tower. Emission levels as low as 10 ppmv, can therefore be achieved at maximum heat input.
The SO2 stripped from the solvent in the regeneration tower is cooled in an overhead condenser and is available at positive pressure for utilization. Since the amine is always in salt form, it is not volatile and the product SO2 is not contaminated by the amine.