Hydrogen Sulfide and Mercury Abatement: Development and Successful Operation of AMIS Technology

Abstract

Enel developed and patented a proprietary technology, named “AMIS,” for the abatement of hydrogen sulfide and mercury emissions, particularly suited to the characteristics of Italian geothermal power plants (featuring a high NCG content, equipped with directcontact condensers and with unattended operation). The first commercial AMIS installation was started-up at the beginning of 2002 in Mt. Amiata area, where environmental concerns are of foremost importance. As of May 2009, 19 AMIS plants are in operation and 3 are under construction; once completed, the gaseous effluents of 23 out of 33 geothermal units (including 2 under construction) will be abated, corresponding to over 80% of the total emissions. The operational experience so far obtained allowed a better understanding of the performances of AMIS plants, as well as of the sulfur chemistry within the process; at the same time, it suggested various technical improvements, some of which have already been applied, while others are still in progress. After a brief description of AMIS technology, this paper presents the main findings derived from many plant-years of operation and the developments that are foreseen. AMIS has proven to be an effective and reliable abatement technology and its use may expand further in the future.