EGB360 - Reservoir Flow Analysis and Pump Design Assignment

This assignment focuses on the design and analysis of a pumping system for transferring water from a reservoir (A) to two other reservoirs (B and C) under different operational modes. The solution begins by determining the pump rating based on flow rates and head. It considers factors such as valve selection, pipe sizes, and the distribution of water flow between reservoirs B and C. The assignment involves drawing a detailed system schematic, calculating head losses, selecting appropriate pipe diameters, and analyzing pump operating points under different flow conditions. The solution demonstrates the use of pump performance curves and system resistance curves to illustrate the behavior of the pumping system. Furthermore, it addresses the throttling of the main suction isolation valve to maintain a required NPSH safety factor and demonstrates the pump's operation under a specific flow condition where all water flows to reservoir C. The assignment provides insights into the practical aspects of pump selection, system design, and operational control in a water distribution scenario.

EGB360 – Plant and Process Design
Water need to be transferred from reservoir A to B and C
The pump shall be between 200 to 250m downstream of reservoir A
The following are the modes of operation, with parameters to be considered for design.
MODE (I)
(Design condition 1)
– Normal flow rate from reservoir A to be 250 litres/second
– Discharge into Reservoir B to be 50 litres/s and into
Reservoir C to be 200 litres/s.
MODE (II)
(Design condition 2)
– Normal flow rate from reservoir A to be 250 litres/second
– Discharge into Reservoir B to be 80 litres/s and into
Reservoir C to be 170 litres/s.
MODE (III)
(All flow to Reservoir C)
– The same number of pumps running as in MODE (I)
– Control valve in Line D-C set to cause all flow running into
Reservoir C, i.e. no water to be discharged into or drained from
Reservoir B.
Tasks:
1. Draw a detailed system schematic for MODE (I), allowing for sufficient valves
(no non-return valves in Line D-B) and at least three 90O bends per pipe
section.
2. Show the selected pipeline diameters and their associated head losses (based
on good engineering practice) in a table and justify the reasons for your
component selection. For MODE (I) & (II)
3. Show the expected pump operating points for MODE (I) & (II) and
demonstrate these by showing pump performance and system resistance
curves. Compare the performance of the two design conditions
4. Determine the amount of the main suction isolation valve to be throttled in MODE
(I) & (II) in order to match an NPSH safety factor of 1.15 for the pumps.
5. Show pump operating points, system resistance curves and control valve
settings for operation in MODE (III).
Solution
We shall find the pump rating for the system, knowing the flow rate and the head
The formula is
Power ( HP )= TDH X Q X SG
3960
Where: TDH stands for the total dynamic head, the height the liquid travels including the
frictional losses, Q is the flow rate in m3/s, SG is the specific gravity for water the value is
1. 3960 is a factor for horsepower conversion.
We shall consider the highest reservoir

1000 X 250
3960 =63.13 HP
This is for the three pumps, we shall assume they have the same ratings, meaning the
pump at the same rate.
Parameters to be considered,
The valves
The pipe sizes
The water needs to be supplied in such a way that the valves will allow 1/5 of water from
A to flow to B, and 4/5 of water to flow in C.
(The diagram)
Question 2
Head loss
Loss of energy head = difference between the levels of the two reservoirs
By using the discharge rates, we shall find the diameters of the pipes
Then find the velocity, by using the continuity equation
Question 3