Combined process

A combined process can also be used to optimize sorbent cost throughout the entire process. A cheap sorbent takes care of most of the abatement, while a highly-efficient sorbent captures the last traces of pollutant later in the process. 

In principle, DSI can be used in combination with all existing FGT processes, including wet or all dry processes. Such combined processes usually have two main purposes: 

• removing a “new” pollutant that cannot be handled by an existing FGT process 
• increasing the removal performance of an existing FGT process 

Removing a “new” pollutant that cannot be handled by an existing FGT process, such as:

• Sorbacal^® SPS injection for selective HF removal in a waste-to-energy plant, using sodium bicarbonate for SO₂ and HCl control.
• Sorbacal^® SP injection for HCl removal downstream from a coal or residue derived fuel fired CFB boiler using limestone for in situ SO₂ removal.
• Sorbacal^® SP injection upstream of a wet scrubber in a coal-fired power plant, for selective SO₃ and/or HF removal to reduce air preheater fouling, corrosion and “blue plume” (sulfuric acid aerosol emission).
• Sorbacal^® Micro dry injection upstream of filtration, for mercury removal in a coal-fired power plant using wet scrubbing for acid gas removal.

Increasing the removal performance of an existing FGT process, such as:

• Sorbacal^® SPS injection at multiple locations in the process for optimized SO₂ removal.
• Sorbacal^® SPS injection in the boiler (FSI) in waste-to-energy plants, for additional SO₂ control before the existing FGT installation (DSI/SDA).