Parallel Pump Calculation

[Falcon03]

How can I calculate my pumps performance in parallel conditions?

In our LPG system we have two pumps (motor/turbine), usually motor pump is running most of the time. The common discharge line will split into tow streams one to rundown (LPG to storage) and the other one back to the column as a reflux.

Based on filed survey, it was noticed that running with a Turbine pump will not delivered the required head, on other word it is not equivalent to the motor pump. More money needs to be spent to upgrade the turbine pump.

We are planning to increase our unit throughput and based on the Engineering study it was found that another motor pump is required to run in parallel to the existing motor pump. Therefore, we are going to run with two motor pumps in parallel in the future.

The question is, how can I ensure that running with a motor and turbine pump in parallel will deliver the required flow for the future case?

We are thinking to carry out a test run now to run both turbine and motor pump is parallel to have a good base line.

What other things that I need to be considered during my testing? Your help in this matter is required. Thank you.

 

[pmover]

first - are existing pumps in good condition? identical? pump rpm? meaning, are they operating as designed?

if so, then is piping system of sufficient size to handle the additional capacity?

is current piping configuration such that the overall flow resistance from pump common inlet piping to common outlet piping the same for each pump?

generally, pumps installed and operating in parallel should have nearly identical performance curves. if not, then the pump with the higher head capability will reduce the capacity of the lower head pump. typically, pumps operating in parallel will have additive flows at same developed head.

i'd be certain of existing installation before installing additional capacity. hence, check pump perf curves, piping installation, etc.

hope this helps!
good luck!
-pmover