Flue gas scrubbing process for sulfur dioxide and particulate emissions preceding CO2absorption

摘要

AbstractThis article describes a 2‐stage scrubbing process which utilizes sodium hydroxide or sodium carbonate as the neutralizing chemical for sulfur dioxide and sulfur trioxide emissions to remove contaminants from gas streams preceding CO2absorption processes.Amine absorption processes are adversely affected by sulfur dioxide in the gas stream, and it is desirable to reduce sulfur dioxide concentrations to less than 5 ppm (vol).Conventional flue gas desulfurization processes do not achieve outlet concentrations at this level. With appropriate controls on pH, ionic strength, and liquid recirculation rates, the sodium alkalies can achieve these outlet concentrations. When concentrations of sulfur dioxide absorbed become sufficiently large to make the economics of a simple throw‐away process uneconomical, the waste solutions can be regenerated in the double‐alkali process by reacting them externally from the scrubbing system with calcium compounds. This process is also described. Particular emphasis is placed on process design for reliability. Materials of construction, process controls, and process chemistry are disc