A variety of complications have arisen from the installation of first generation ACI systems. CPS Energy is currently installing ACI on its two largest units. CPS and Sargent & Lundy reviewed experiences of operating ACI systems and developed specifications building on lessons learned, Kevin Schaefer and Holly Hills of Sargent & Lundy and Shane Bemis of CPS Energy told the Electric Power 2013 audience.

Process issues involved PAC containment, PAC flowability and foreign materials. PAC behaves like a liquid, so it is necessary to design for a liquid. Characteristics vary from one PAC supplier to another, so design for a range of characteristics. A strainer needs to be installed on the silo fill line to remove foreign objects picked up in transit (a plastic bag is the worst case).

Equipment issues include blower type, blower size and speed, rotary valves, gravimetric feeders, eductors, diverter valves. Distance must be considered between the silo and injection point in determining the blower. Variable-frequency drives on the blower give better control and reduce PAC consumption. For rotary valves, specify high-head and for highly-fluid material. Gravimetric feeders are essential and need to control injection rates as dictated by emission monitors. Inclusion of a vent in the eductor feed pipe will help avoid uncontrolled carbon flow. Two 3-way diverter valves will simplify operation and reduce maintenance.