Optimizing Pump Mixing in a Dual Pump System for Titrations

[LtStorm]

So, this seemed most appropriate for this forum, as it's essentially a question about pumps, pressures, and fluid mechanics.

The set up I have that this question pertains to;

There are two pumps that have lines running to a T-joint with a small chamber to allow for mixing before exiting into an analyzer.

To bring a bit of chemistry into this, what I'm trying to do is run a titration using this setup; I have one solution in Pump A's reservoir, and a different solution in Pump B's reservoir. Pump A's concentration needs to be held constant, while Pump B's concentration needs to be varied. I'm trying to figure out if I need to run both pumps at the same rate, and change the concentration of Pump B's solution, or if I can simply vary the rate of Pump B to get the same effect.

The question in the end is; if Pump B runs slower than Pump A, will mixing still occur effectively, or will Pump B be unable to effectively deliver its solution to the mixing reservoir with Pump A's solution carrying it into the analyzer before it has a chance to mix in the chamber appreciably, and does the rate of Pump B in comparison to Pump A have an effect on that mixing?

 

[Q_Goest]

Assuming both pumps can produce sufficient head to flow into the mixing T, it can be made to work. Reducing flow of pump B can be done in different ways. If it is a centrifugal pump, you may be able to change flow enough simply by throttling the inlet or outlet. If that doesn't get you enough variation in flow rate, you can go to a recycle loop which will work with any type of pump. The last thing you can do is to have a high pressure reservoir downstream of pump B that acts as a buffer. The reservoir would be pumped up to a shut off set point and back on at a lower set point some where above the pressure you need. The flow from the reservoir would then be modulated through a control valve.