Ratio control

There are a number of possible ways to do proportional/ratio control. The plant I work in uses several ratio control schemes. The first thing we need in order properly answer your question is some system specific info.

What is the min and max flow rate of each stream?

What are the streams? Water? Acid? Milk?

Is this an existing system being modified or a new build?

Are you looking for PLC control or some type of local controller?

Is the mixing of the two streams to occurr in a pipe or in a tank?

The more information you give about your system the better the information you receive will be.

Richard

It's quite simple. Stream B is modulated to provide a fixed flow ratio to stream A. Stream A needs a flowmeter. Stream B needs something that con modulate the flow, like a dosing pump, a gear pump or a control valve.

There's probably more to be revealed here...

Now seeing what you are doing, I'll try to help. I once had an acid wash spray system that I wanted to dispense to the sewer. Not a problem said the county officials, just make the Ph 7.4 by the time is gets to the city system. I put a mixer/meter on the drain, knowing the flow of the acid, I dumped a 'base' in the sewer at exactly the same point the acid was being dumped and it worked great.

But what you describe sounds like two pipes, one with inconsistent flow and the other consistent. A cheap and easy fix would be to put an accumulator on the inconsistent flow followed by a orifice that would even out the flow, and then just meter in the other material.

Just thinking out loud here...

see the process control systems by fg shinsky

Ratio control system

ratio control system are feedforward systems wherin one variable is controlld in ratio to another to satisfy some highr-levl objectivs. for example additives are controlld in ratio to the priciples component in a blend, to maintain the composition of the the blend constant. the primary controlld variable is then composition, which is a fuction of the ratio of the component. however, it canot always be meassured, in which case it canot be controld by feedback.

in ratio control system.then, the true cotrolld variable is the ratio R of two measured variables X and Y

R=X/ Y

Your answer is a good text book answer but I'm still hoping thought for a little more input from the original poster so that a more specific set of possible control schemes can be discussed.

pid is ordinary control way in dustry. you can jfind it in most of textbook but experience is another things.

try again and agian. you will find optimum coefficient you choose.