What is the purpose of activated carbon in mercury removal systems?

The purpose of activated carbon in mercury removal systems is to selectively adsorb mercury from the natural gas stream. Activated carbon is a form of carbon that has been processed to have a very large surface area, typically in the range of 500 to 1500 square meters per gram. This large surface area provides a vast number of adsorption sites where mercury atoms can bind to the carbon material. The mercury removal process involves passing the natural gas stream through a bed of activated carbon. The mercury atoms in the gas phase are attracted to the surface of the activated carbon due to van der Waals forces and other chemical interactions. They then bind to the carbon surface, effectively removing them from the gas stream. The activated carbon is typically impregnated with sulfur or other chemicals to enhance its mercury adsorption capacity. The sulfur reacts with the mercury to form mercury sulfide, which is strongly bound to the carbon surface. Once the activated carbon becomes saturated with mercury, it must be replaced or regenerated. The spent activated carbon is typically disposed of in a landfill that is designed for hazardous waste, or it can be sent to a facility for mercury recovery. Activated carbon is a cost-effective and reliable method for mercury removal in LNG plants, ensuring the integrity of downstream equipment and the quality of the LNG product.