Water injected upstream of the ACC can drain back into the steam turbine causing turbine damage if proper drainage provisions are not included. Also the injection water should be demineralized and deaerated to prevent adding unacceptable dissolved solids and non-condensable gases to the condensate. I have seen plants where water has been injected in steam turbine exhaust hood sprays to protect steam turbines from overheating during periods of high backpressure.
