Step 1: Set the desired flow rate for each pipe

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Step 1 Set the desired flow rate for each pipe
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Step 2 Click on the stream which you wish to
size the pipe. Select Sizing from the menu, then
select Pipes
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Step 3 Click on Select streams from flowsheet.
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Step 4 Click on Typical sizing for single
phase. Then enter the Pipe Schedule. Schedule
40 is used for pipes less than 150 psig.
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Step 5 Note the Nominal Dia. If it is in feet,
you can change the units to inches under the
Engineering Units menu
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Step 6 Select the stream, then click on Sizing,
then Control Valve
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Step 7 Enter the downstream pressure. Assume
that it will be 10 psi less than the stream
pressure
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Note the Capacity Coefficient, Cv
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Insert a control valve in the stream, then enter
the Valve flow coefficient (Cv), select Fix valve
position, adjust flow rate in the Operating mode,
and then enter 50 for the Valve position .
Enter the downstream pressure even if it is not
known.
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Run the program. You can change the valve
position to give the desired flow rate.
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Insert a node before and after the control valve
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For the upstream node, set the Mode to Fixed
Pressure, and enter the pressure at the node.
Select Free inlet stream for the inlet and Flow
set by UnitOp for the outlet
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Enter the outlet pressure for the outlet node,
and Flow set by UnitOP for the inlet and Free
Outlet stream for the outlet.
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Open up the control valve menu and delete the
Downstream pressure. Then enter the node number
for the Destination ID and Node Pressure for the
variable
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Insert a Pipe Simulator and another node.
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Click on the pipe, and enter the Method, the
Sizing option, the Pipe diameter, Pipe Schedule,
Pipe Length, and Pipe Material
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Reset the Node settings for the node before the
pipe.
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For the last node, use the following parameters
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Insert a PID Controller at the outlet of the last
node
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Activate the controller, enter the desired set
point, the sensor min and max, the proportional
band, the control valve ID number, select Reverse
for the controller action, and select what is to
be measured. Make sure the Engineering Units are
set for the units that you desire for the set
point.
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Open up the control valve dialog box and enter
the Controller ID
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Click on the Run menu and select Convergence.
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Select Dynamics under the Steady State/Dynamics
menu
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Select Dynamics under the Run menu.
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Click on Set run time.
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Enter the Run Time and Step size in the Step 1
menue
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Click on Record Streams and enter the streams
which you wish to plot
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Select the frequency you wish to plot and then
click on Plot Stream Properties
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Check the properties you wish to plot. After
clicking OK, click on Run from Initial State
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Continue to decrease the Proportional Band until
your plot looks similar to the above
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Start off with a large Integral time for the PID
controller and decrease it until a stable value
is obtained as quickly as possible.
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Assignment Set up a piping network that can
deliver 20 gpm of water at 75 F to each of three
floors of a building. One floor is at a 50 ft
elevation, the second is at 30 ft, and the third
is at 15 ft. Water is available at 60 psia. The
outlet pressure at each floor will be at 14.7
psia. Size the piping and control valves under
steady state conditions without using the nodes.
Once the pipes and valves are sized, begin to
optimize the PID tuning one valve at a time. If
you try to do it all at once, you will be
guaranteed to have problems.