Piping System Model

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Navigation: Main Page -> Models -> Pressure Changing Models


General Description

The Piping System Model is used in dynamic projects with Transfer mode. It allows the user emulate a full piping system, including Pumps, Valves, Pipe lengths, etc in a single Piping System model. The user specifies the number and type of sub-units in the piping system and can configure each sub-unit individually. The user must configure the individual sub-units within the Piping System Model so that they comprise a reasonable system.

The piping system model calculates the pressure drop across each sub-unit, and hence across the entire system. If required it will also calculate the estimated flow through the system, based on the calculated pressure drop.

The available sub-units in a Piping System Model are:

  • Head - Elevation Head - the head due to the height of the liquid at the start of the piping system;
  • Pipe - pipe lengths and fittings can be included - the pressure drop in the pipe due to change of height, friction losses, etc. will be calculated;
  • Pump2 - pressure boost provided by a pump; and
  • Valve2 - pressure drop provided by a valve.

Notes

  1. The Pump and the Valve have control settings that the user may dynamically change. These settings will change the calculated pressure drop of the system.
  2. The Piping System Model will NOT automatically adjust the flow, but can be set to calculate the estimated flow through the system. This estimate can then be used to set the actual flow in the system, if required.
  3. The Piping System Model is designed to emulate an entire piping length, without any split flows.
  4. The Piping System Model requires a single input and a single output and will not operate unless both of these streams are connected. The physical location of the connections is not important - the user may connect the streams to any position on the drawing.

Inputs and Outputs

Label Required
Optional
Input
Output
Number of Connections Description
Min Max.
Input Required In 1 1 Input stream to Piping System Model.
Output Required Out 1 1 Output stream from Piping System Model.

Model Theory

For Valve and Pump theory please see:

Data Sections

The default access window consists of the following sections:

  1. PipingSystem tab - Allows the user to insert sub-units and displays the calculated results.
  2. Control tab - Allows the user to set any valve positions and Pump speeds.
  3. Settings tab - Allows the user to specify the sub-unit methods and enter the required data.
  4. Info tab - contains general settings for the unit and allows the user to include documentation about the unit and create Hyperlinks to external documents.
  5. Links tab, contains a summary table for all the input and output streams.
  6. Audit tab - contains summary information required for Mass and Energy balance. See Model Examples for enthalpy calculation Examples.


Piping System Page

Unit Type: PipingSystem - The first tab page in the access window will have this name.

Tag / Symbol
Input / Calc
Description/Calculated Variables

Common Data on First Tab Page

Options

On Tick Box This allows the user to disable the unit. If the unit is Off then the pressure drop across the unit = 0.

Options (Flow Estimate Calculations)

FlowEstimateMethod None The user does not wish to calculate the estimated of the flow through the unit. The pressure drop WILL be calculated.
Simple The flow through the unit will be calculated with no time delays or transient effects. This is useful for short piping systems.
User Damping The flow through the unit will be calculated with a time delay, or transient effect. The user may set the fraction of damping required.
Length Damping The flow through the unit will be calculated with a time delay, or transient effect, based on the length of the piping system. This is useful where the user wishes to emulate a long pipeline so that a change in feed pressure does produce an instantaneous flow change in the pipe system.
DampingRate Input Visible if User Damping is the Flow Estimate Method selected. The required amount of damping on the estimated flow. 0% represents no damping (changes are instantaneous - so equal to using Simple), and 99% represents large damping.
SpecifyTargetP Tick Box The user may specify a target outlet pressure from the system. If this is NOT enabled, then the outlet pressure is assumed to be the system inlet pressure. This is not visible if the user selects None as the Flow Estimate Method.
TargetExitP Input If SpecifyTargetP is enabled then this field is visible and the user may set the required outlet presusre from the piping system.

Sub-unit Selection

SegmentCount Input The user may define the number of sub-units in the Piping System Model. For example, if a system consists of a Valve, Pump, Valve and pipe then the number of sub-units, or segments = 4.
ReNumber Button This re-numbers all of the sub-units so that they are all in ascending order.
Segment Specification
Type List The user may choose any of the sub-units that are available, i.e. Head, Pipe, Valve or Pump.
Insert Button The user may insert a new sub-unit above the current sub-unit. This will automatically increase the Segment Count. The default sub-unit that is inserted is a Pipe, but the user may change this by selecting any of the available sub-units from the drop down list.
Remove Button The user may remove the sub-unit from the Piping System Model. This will automatically decrease the Segment Count.
Up Button The user may move the current sub-unit up in the order of sub-units. The sub-unit number will NOT change, i.e. Pipe3 can be moved above Pipe1. The user may click on the ReNumber button to automatically number the sub-units in ascending order.
Down Button The user may move the current sub-unit down the order of sub-units. The sub-unit number will NOT change, i.e. Pipe1 can be moved below Pipe2. The user may click on the ReNumber button to automatically number the sub-units in ascending order.

Results

Overview
Feed.Qm Display The mass flow through the Piping System Model.
Feed.T Display The inlet temperature to the Piping System Model.
Feed.P Display The inlet pressure to the Piping System Model.
Sub-unit(i).Po Calc The pressure from sub-unit(i), where this could be Head, Valve, Pump or Pipe. The pressure from each sub-unit will be displayed.
Prod.P Calc The exit pressure from the Piping System Model.
Prod.T Calc The exit temperature from the Piping System Model.
Totals
Sub-unit(i).dP Calc The pressure change across sub-unit(i), where this could be Head, Valve, Pump or Pipe. The pressure change across each sub-unit will be displayed.
dP Calc The total pressure change across the Piping System Model.
PDrop Calc The pressure drop across the entire Piping System Model.
PBoost Calc The pressure boost across the entire Piping System Model.
Closed Tick Box If this is True, then a sub-unit, either a Valve or Pump, is set to 0% and is the flow estimate = 0.
Head Calc The calculated Head from the Piping System Model.
HeightChange Calc The calculated change in Height across the Piping System Model (-ve indicates a drop from Feed to Product)
Relative Heights
Feed Calc The relative height of the feed to the Piping System Model.
Sub-unit(i).Out Calc The relative height of sub-unit(i), where sub-unit can be Head or Pipe. All Head and Pipe sub-units will be displayed.
Prod Calc The relative height of the product of the Piping System Model.
Flow Estimate These fields are only visible if the user has selected a Flow Estimate method.
Qm Display The actual mass flow through the Piping System Model.
QmEstState Display The state of the Piping System Model estimate. This lets the user know what state the model is in, i.e. OK, No Flow, sub-units closed, etc.
ExtraTarget.dP Calc The extra pressure drop required IF the user has specified a Target Exit Pressure from the unit.
TotalK Calc The calculated resistance, or loss coefficient value, K, of the Piping System Model.
TotalHead.dP Calc The total pressure change across the Piping System Model.
DiamUsed Calc The piping diameter used to calculate the velocity and estimated flow through the Piping System Model.
VelocityEst Calc The estimated velocity in the Piping System Model.
QmEst Calc The estimated mass flow rate through the Piping System Model.
QvEst Calc The estimated volumetric flow rate through the Piping System Model.
PrevVelEst Calc The velocity in the Piping System Model estimated in the previous iteration. (This is only useful if Damping is used.)

Control

If the user selected either a Pump or a Valve as one of the sub-units and a controlled mode for either of these, then this tab will allow these units to be controlled.

Please see the relevant sub-unit for a description of the fields:


Settings

The user must configure each sub-unit that is specified on the first tab.

Please see Valve Settings and Pump Settings for the configuration of the Valves and Pumps.

The settings for Heads and Pipes are described below.

Symbol / Tag
Input / Calc
Description/Calculated Variables
Head
On Tick Box This allows the user to disable the Head. If the Head is Off then Head = 0.
EquipID Input This field is optional. The user may type in an unique ID for this, example Head Tank.
Height / H Input The actual Elevation Head required. This calculates the pressure boost due to elevation as material enters the Piping System.
Pipe
On Tick Box This allows the user to disable the Pipe. If the Pipe is Off then pressure drop across the pipe = 0.
EquipID Input This field is optional. The user may type in an unique ID for the Pipe.
OpType Fixed dP The user specifies a fixed pressure change across the Pipe. This will be independent of flow.
Fixed Drop The user specifies a fixed pressure drop across the Pipe. This will be independent of flow.
Fixed Boost The user specifies a fixed pressure boost across the Pipe. This will be independent of flow.
Darcy Use the Darcy equation to calculate pressure drop. With this method pressure drop is a function of flow.
DeltaHeight / dH Input The required height difference between the pipe entry and exit. A negative values indicates that the exit is lower than the entry.
Fixed dP Fixed Drop and Fixed Boost - The following field is visible for these three modes.
Fixed.dP/Drop/Boost Input The required pressure change, drop or boost (depending on the mode selected) across the Pipe.
Darcy The following fields are visible with this mode.
Diameter / Diam Input The required internal pipe diameter.
ScaleBuildup / Scale Input The required scale build up thickness in the pipe. Note, this values will be multiplied by 2 and then used to decrease the actual internal diameter of the Pipe.
MinorK Input The K value for any fittings on the pipe.
KMethod User Pipe K The user specifies a K value for the pipeline.
Length and Friction F The user specifies the pipe length and a friction factor. SysCAD will then calculate the equivalent K value.
Length, Colebrook FricF The user specifies the pipe length, Viscosity and roughness. SysCAD will then calculate the friction factor using the Colebrook equation.
Length, Churchill FricF The user specifies the pipe length, Viscosity and roughness. SysCAD will then calculate the friction factor using the Churchill equation.
User Pipe K The following field is visible if this method is chosen.
UserPipeK Input The required K value for the Pipe.
The following 2 fields are visible for the other methods.
Length / L Input The required Pipe Length.
FittingsLength / FitL Input The equivalent pipe fittings Length.
Please do not include a value here for fittings if they are already included under MinorK.
Length and Friction F The following field is visible for this method.
UserFricFactor / UserFricF Input The required friction factor.
Length, Churchill and Colebrook Friction Factor The following fields are visible for both of these methods.
Viscosity Input The viscosity of the material flowing through the pipe.
Roughness Input The roughness of the pipe.
Valve
Valve Settings
Pump
Pump Settings

Adding this Model to a Project

Insert into Configuration file

Sort either by DLL or Group.

 

DLL:

Piping2.dll

Units/Links

Piping: Piping System

or

Group:

Mass Transfer

Units/Links

Piping: Piping System

See Project Configuration for more information on adding models to the configuration file.


Insert into Project

 

Insert Unit

Piping

Piping System

See Insert Unit for general information on inserting units.

Example - Entering Elevation Information

Piping System.png
  • Feed_Tank - Assume at 0 m elevation
  • Feed_Pump - Piping System : Seg06 (Pipe4 - Pipe to Head tank) has delta height (dH) of 15 m
Piping System2.png
  • Head_tank - Assume at 15 m elevation (tank height 2m) - NOTE that we can't enter an elevation for the tank here, so we need to provide the information in the next unit where the change of height occurs.
  • FCV_001 - Piping System : Flow control valve to Area1 (See first picture above)
    • Head - 16.7m (this reflects the elevation head from head_tank, assuming tank is 85% full ) - this will calculate the pressure at the start of the FCV_001 piping system.
    • Destination elevation is 5m higher