Gaston demonstrates substantial mercury removal with sorbent injection

Draft legislation indicates that new regulations may require mercury removal efficiencies as high as 90% from existing sources. With regulations rapidly approaching, it is important to concentrate efforts on the most mature retrofit control technologies. Injection of dry sorbents such as powdered activated carbon (PAC) into the flue gas and further collection of the sorbent by ESPs and fabric filters is commonly used in municipal waste incinerators for mercury control and represents the most mature and potentially most cost-effective control technology for power plants. Under a DOE/NETL cooperative agreement, ADA-ES is working in partnership with several other companies on a field evaluation program of sorbent injection upstream of existing particulate control devices for mercury control. Gaston Unit 3 was chosen as the first test site because COmpact Hybrid PArticulate Collector (COHPAC) represents a cost-effective retrofit option for utilities with electrostatic precipitators (ESP). COHPAC is an EPRI patented concept that places a higher than normal air-to-cloth ratio baghouse downstream of an existing ESP to improve overall particulate collection efficiency. Results of this test are presented.