Split and Blend - Controlling Volumetric Flow via Branching Pipelines
Split and Blend - Controlling Volumetric Flow via Branching Pipelines
(OP)
Hello Everyone!
Suppose I have 3+1 VFD pumps abstracting 18000 m^3/day of water from a filtered water tank. The pumps discharge at a common header. The header then branches into two pipes, one goes to disinfection tank, one goes to the RO then to the disinfection tank. See figure below:

Consider 3 general cases:
Case 1-Water is good: All the water goes to disinfection tank directly.
Case 2-Water is bad: All the water goes to RO, then to disinfection.
Case 3-Water is average: Water is split and blended, say 70% goes to RO and 30% goes to disinfection.
For case 3, will the above configuration work? The valves at the header going to RO and disinfection are both modulating.
Thank you for any opinion/advise!
Suppose I have 3+1 VFD pumps abstracting 18000 m^3/day of water from a filtered water tank. The pumps discharge at a common header. The header then branches into two pipes, one goes to disinfection tank, one goes to the RO then to the disinfection tank. See figure below:

Consider 3 general cases:
Case 1-Water is good: All the water goes to disinfection tank directly.
Case 2-Water is bad: All the water goes to RO, then to disinfection.
Case 3-Water is average: Water is split and blended, say 70% goes to RO and 30% goes to disinfection.
For case 3, will the above configuration work? The valves at the header going to RO and disinfection are both modulating.
Thank you for any opinion/advise!





RE: Split and Blend - Controlling Volumetric Flow via Branching Pipelines
The two modulating valves would have to have different control loops and controlled from different elements, but would interact as well. Any change on one valve will cause a change to occur in the other or for the pump speed to change.
The pumps would have to be able to supply enough flow and pressure to make it all work.
The valves would have to have enough sensitivity and control to achieve the necessary flow etc.
I would wonder whether it might be easier to have a couple of pumps dedicated to each of the outputs but have some interconnects and manual valving to allow some cross overs if needed to provide duty/standby type arrangements. Although this will still have some control complexity it would still be easier than the above control scenario.
Regards
Ashtree
"Any water can be made potable if you filter it through enough money"
RE: Split and Blend - Controlling Volumetric Flow via Branching Pipelines
RE: Split and Blend - Controlling Volumetric Flow via Branching Pipelines
If you go with two valves, I would look for a control scheme where one valve is alway 100% open.
RE: Split and Blend - Controlling Volumetric Flow via Branching Pipelines
RE: Split and Blend - Controlling Volumetric Flow via Branching Pipelines
RE: Split and Blend - Controlling Volumetric Flow via Branching Pipelines