Controlling RAS
Controlling RAS
(OP)
The design has 4 clarifiers - 2 @ 60 ft diam, 2 @ 90 ft diam. Think of two separate trains/systems where the RAS is drawn from the bottom of one of the 60 ft and one of the 90 ft clarifiers by pipes that are manifolded together that connect to a common suction header at the RAS pump station. The pipes for the RAS is the same diameter (10-inch) from the 60 ft and 90 ft clarifiers. A mirror image occurs with the other two clarifiers (mainfolded together and tie into a common suction header at the RAS pump station). Two separate trains, but utilizing the same RAS pumps station. What is the cheapest way to control the RAS? What about plug valves installed on each of the RAS lines, which would allow the operators to adjust the RAS return from each clarifier.





RE: Controlling RAS
I would suggest that if you need more control you're on the right track and adding control plug valves, flow meters and bypasses, isolation valves etc would be appropriate. Maybe pinch valves but I doubt it.
RE: Controlling RAS
If you have a new project, then you probably want to run the sludge piping separately to a common sump. At the common sump, you can use telescopic valves on each separate sludge line or a separate weir gate on each of the sludge lines. At startup, you adjust so that the flow is equalized.
Manifolding the pipes together before the sump is probably not a good solution since you have no guarantee on the flow from each separate pipe entering the manifold.
RE: Controlling RAS
RE: Controlling RAS
RE: Controlling RAS