I need a some help on a process that I'm currently working on which involves the control of pH. This is my first time working with pH and I'm pretty concerned about how non-linear it is. I'm using a Rosemount 5081 that is connected to a Rosemount 3900 pH sensor. The 5081 is outputting a 4-20mA signal back to my control logix chassis. The 4-20mA signal is going to a 1756-IF8 and the controller is a 1756-L71 with 2Mbytes memory.
The pH sensor is located on the backside of a tank that is being mixed. There are two metering pumps that will pump either acid or base into the process before it goes into the tank for mixing. The customer has a pretty wide range for what is acceptable on pH, 5.5-9.5.
I going down the path of using a PIDE block but I'm not sure how to implement everything. Right now I'm trying to set something up so when the PV rises above 7 the acid pump kicks on and runs, which would be direct acting (E = PV-SP) and visa versa for the base pump, reverse acting (E = SP-PV).
Am I even on the right path? Do I need to take the titration curves into account? Can I do this with one PIDE block? If I'm just dead wrong let me know, any suggestion would be greatly appreciated. Thanks!
The pH sensor is located on the backside of a tank that is being mixed. There are two metering pumps that will pump either acid or base into the process before it goes into the tank for mixing. The customer has a pretty wide range for what is acceptable on pH, 5.5-9.5.
I going down the path of using a PIDE block but I'm not sure how to implement everything. Right now I'm trying to set something up so when the PV rises above 7 the acid pump kicks on and runs, which would be direct acting (E = PV-SP) and visa versa for the base pump, reverse acting (E = SP-PV).
Am I even on the right path? Do I need to take the titration curves into account? Can I do this with one PIDE block? If I'm just dead wrong let me know, any suggestion would be greatly appreciated. Thanks!