Compound Loop Control

[kj]

Has anyone know the matimatically details of "Compound Loop" control for water disinfection? I am appreciated if anyone can give me an answer or direct me of where to look for the info.

Thanks,

KJ

 

What exactly do you mean by "compound loop"? Does it mean that you have more than one parameter at a time that you are monitoring/controlling? If you are talking about dosing disinfectant for water/wastewater treatmant, the process depends on flowrate, feed concentration and residual.

 

[kj]

Some people calls it "Dual Signals Control". In an early 1960, a company called Wallace & Tiernan introduced a control scheme called "Compound Loop Control" and used it to control chlorine in a chlorination process. This control strategy based upon two independent signals and two seperate control loops. For example; a metering pump with a pump speed and a stroke lenght control, you can control the speed of the pump with influent flow pacing(open loop.) And, also you can control the stroke lenght of the pump with the residual feedback(close loop)signal at the same time.

Now, the control strtegy has evolved into "Dual Signals Control". Still most of the people called it "Compound Loop". All signals, flow pacing, chlorine residual feedback and a residual set point from the Operator are input into this type of controller. The controller send out only one analog output signal that it can be used to control a single quantity final control element such as a chlorine gas valve or a variable speed metering pump.

What is happened inside of this type of controller in mathematical details? I am appreciated any info or advice that you can give me.

Sincerely,

KJ