Parellel Pumping
Parellel Pumping
(OP)
Hi there sorry I have not been able to make a sketch and post here. I's like to ask the experts a question.
background: I have two centrifugal pump non-identical. One is pumping side-draw off a de-C3 tower (P-1) and other pumping overheads from a de-C4 tower (P-2). The product from both pumps combine and go to MEROX. I feel we need a pressure transmitter at the junction so the flow control from one pump will cascade control with a fixed pressure thus you have a steady state flow going to MEROX.
Seem obvious to me but I have the instrument and controls guy that says there is no need for pressure transmitter as both pumps will automatically (magically) arrive at the junction at the same pressure.
I may not have presented the picture as you need it but thanks for your comments.
Madi
background: I have two centrifugal pump non-identical. One is pumping side-draw off a de-C3 tower (P-1) and other pumping overheads from a de-C4 tower (P-2). The product from both pumps combine and go to MEROX. I feel we need a pressure transmitter at the junction so the flow control from one pump will cascade control with a fixed pressure thus you have a steady state flow going to MEROX.
Seem obvious to me but I have the instrument and controls guy that says there is no need for pressure transmitter as both pumps will automatically (magically) arrive at the junction at the same pressure.
I may not have presented the picture as you need it but thanks for your comments.
Madi





RE: Parellel Pumping
Is the pressure controlled anywhere downstream of the junction point? We need a sketch to understand the configuration better.
Dejan IVANOVIC
Process Engineer, MSChE
RE: Parellel Pumping
What controls the flow from each pump? Does each pump have a control valve or VSD?
As a chem eng/metallurgist the first part of any answer I give starts with "It Depends"
RE: Parellel Pumping
You probably have a control valve on the discharge line of each pump (upstream of where the streams meet). Let's illustrate the point I'm making by use of an extreme example. Say the pressure at the convergence point is 50 psig. Now let's say that Pump-A is putting up 100 psig at its discharge. Regardless of whether Pump-B is putting up 200, or 500, or 15000 psig at it's discharge, this has no affect on the pressure at the downstream side of the Pump-B control valve (or at the convergence point where the pressure is 50 psig). Instead, this excess pressure from Pump-B is simply being wasted across the control valve.
Once a stream gets past the control valve, the pressure in the pipeline is only influenced by the resistant in the downstream system. It has nothing to do with the driver, whether that is a pump or a compressor.
RE: Parellel Pumping
Gabriel Castaneda, P.E.
http://www.gabcheminc.com
RE: Parellel Pumping