The production of ammonia requires the removal of carbon dioxide (CO2) to ppm levels. Vapor streams containing acid gases enter and are put in contact with a lean solvent in an absorber column. The lean solvent absorbs the acid gases and exits the bottom of the column as a rich solution, which is then sent to a regenerator column to strip the acid gases from the solvent so it can be recycled. Many industries, including oil refining, natural gas plants, LNG, and hydrogen plants require these processes.
While there are many treating processes available, no single process is ideal for all applications. Usually the process licensor selects the most suitable solvent based on feed conditions such as composition, pressure, temperature, and the type of impurities. Additional considerations for solvent selection are process economics, reliability, and environmental constraints.
With high liquid rates, random packing is well-suited to handle this application. Some solvents used in acid gas removal tend to foam, and random packing is better equipped to handle foaming as compared to trays because the vapor is not injected into the liquid phase at a locally high velocity. Structured packing can be utilized in acid gas removal when the liquid rate is low enough for the packing to handle.
Trays are generally more tolerant to fouling than packed tower internals. In severe fouling cases, Koch-Glitsch offers PROVALVE® trays or FLEXITRAY® valve trays with VG-10 valves. Both large fixed valve types offer improved reliability. Using trays initially also results in tower sizes that can later be revamped with SUPERFRAC® trays or packings to increase capacity.