Valve 1 - Dynamic Simple

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

Related Links: Valve 1 in Steady State and Dynamic Transfer Mode


General Description

This page is for project running under

Network solution - Dynamic and Flow Calculation - Simple mode.

The valve model will deliver flow based on the user specified capacity and opening position. In this mode, the pressure is ignored.


For Dynamic Transfer mode, please refer to Valve1.


Diagram

Valve image001.gif

The diagram shows the default drawing of the Valve, with the required connecting streams. The unit will not operate unless all of the above 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 valve.
Output Required Out 1 1 Output stream from valve.

Model Theory

The valve is a constant enthalpy process.

Step 1) Enthalpy can be calculated from the inlet conditions.

Step 2) Outlet temperature can be calculated from enthalpy and outlet pressure.

Data Sections

Summary of Data Sections

  1. Valve-1 tab - Contains general information relating to the unit.
  2. VLE - Optional tab, only visible if the VLEquilibrium is enabled in the Evaluation Block.
  3. Info tab - Contains general settings for the unit and allows the user to include documentation about the unit and create Hyperlinks to external documents.
  4. Links tab, contains a summary table for all the input and output streams.
  5. Audit tab - Contains summary information required for Mass and Energy balance. See Model Examples for enthalpy calculation Examples.

Dynamic Valve1 Page

Unit Type: Valve-1 - The first tab page in the access window will have this name.

Tag / Symbol Input / Calc Options Description/Calculated Variables
Common Data on First Tab Page
Qm Calc   The total mass of material flowing through the valve.
Qv Calc   The total volumetric flow of material flowing through the valve.
NQv Calc   The normalised volumetric flow through the valve. The volume is calculated at Normal Temperature and Pressure (NTP), default values are 25C and 101.325kPa. This is only relevant for flows containing vapours.

NTP can be specified by the user in the configuration file (see Project Configuration).

QmPrvPB Calc    ??
T Calc   The temperature of material flowing through the valve.
Rho Calc   The density of material flowing through the valve.
NRho Calc   The density of material of material flowing through the valve at Normal Temperature and Pressure (NTP).
 
PiEst Calc   The estimated Pressure at the inlet of the valve.
Pi Calc   The actual pressure at the inlet of the valve.
dP Calc   the pressure change in the valve.
Po Calc   The actual pressure at the outlet of the valve.
PoEst Calc   The estimated Pressure at the outlet of the valve.
 
VLEquilibrium List box   Vapour Liquid Equilibrium (VLE) is enabled here. If this is 'On' then the associated page, VLE becomes visible and may be configured.
Note: This option may automatically adjust the species make-up.
 
Eqn...
Group Default   Using the valve group of equations.
AsMass Tickbox On Allows the user to enter the valve Capacity in mass flow, Qm.Rqd will be settable.
off Allows the user to enter the valve Capacity in volumetric flow, Qv.Rqd will be settable.
 
Qm.Rqd Input/Calc AsMass=On The required valve Capacity in mass flow if the valve is 100% opened.
Qv.Rqd Input/Calc AsMass=off The required valve Capacity in volumetric flow if the valve is 100% opened.
CapacityCtrl List Box Off NOTE in Dynamic Simple mode this has no effect
ByMass NOTE in Dynamic Simple mode this has no effect
ByVolume NOTE in Dynamic Simple mode this has no effect
 
Eqn.Nominal... NOTE THIS SECTION HAS NO EFFECT ON DYNAMIC Simple MODE
Method List Box None No pressure drop
Liner Linear Pressure drop - NOTE in Dynamic Simple mode this has no effect
EqualPerc Pressure drop with pressure drop proportional to flow - NOTE in Dynamic Simple mode this has no effect
QuickActing Pressure drop based on user specified data - NOTE in Dynamic transfer Simple this has no effect
DP Input   The required pressure drop when the valve is opened.
Qm Input/Calc AsMass=On Used to work out pressure drop required (above) when the valve is opened.
Qv Input/Calc AsMass=Off Used to work out pressure drop required (above) when the valve is opened.
Posn...
Type List Box Position Allows the control of the valve on/off and % opened.
Pos & Stroke Allows valve to ramp up to its opening position in the specified valve opening time
Stroke Opn/Cls Allows the valve to ramp up/down on opening position during open and close, instead of reaching its full opening in one single iteration.
Mode List Box Active Displays minimum fields for normal operation of the valve
Command(Latch) Displays additional fields for control of the valve, usually used when connecting to PLC or operating Systems
Command(State) Displays additional fields for control of the valve, usually used when connecting to PLC or operating Systems
Postion, the following field is visible with this mode.
On Tickbox   Toggles the valve on/off
N/C Tickbox   No backward flow allowed
Actual Calc   The actual valve % opened.
Reqd Input   The required valve % opened.
OpenCmd Tickbox   Signals the valve to open, usually used when connecting to PLC or operating Systems
CloseCmd Tickbox   Signals the valve to close, usually used when connecting to PLC or operating Systems
LatchCmds Tickbox   Latch command, usually used when connecting to PLC or operating Systems
LatchState Input   Latch state, usually used when connecting to PLC or operating Systems
Open Feedback   confirms the valve is opened, usually used when connecting to PLC or operating Systems
Closed Feedback   confirms the valve is closed, usually used when connecting to PLC or operating Systems
Manual Input   Used to override the valve opening, used mainly in control logic / PLC testing.
MinOpening Input   Sets the valve Min % opened limit.
MaxOpening Input   Sets the valve Max % opened limit.
LeakOpening Input   Sets the valve Leak % opened limit.
Physical Feedback   The actual valve opening
ReverseAction Tickbox    ??
Stroke Opn/Cls - Command(Latch) or Command(State), the following extra fields are visible with this mode. Usually used when connecting to PLC or operating Systems
Permissive Tickbox   Toggles the valve on/off
OpenCmd Tickbox   Sends the valve open signal
CloseCmd Tickbox   Sends the valve close signal
OpenInvert Tickbox   Sends the valve open invert signal ??
CloseInvert Tickbox   Sends the valve close invert signal ??
Pos & Stroke, the following extra fields are visible with this mode.
StrkTime Tickbox   The time it will take for the valve to get to its required % opening
Stroke Opn/Cls, the following extra fields are visible with this mode.
CloseTime Input   The time it will take for the valve to close.
LoOpen Feedback   Signals the valve is at low opening position if it is less or equal to the LoOpenLimit
HiOpen Feedback   Signals the valve is at high opening position if it is greater or equal to the HiOpenLimit
LoOpenLimit Input   Sets the valve's low open position limit
HiOpenLimit Input   Sets the valve's high open position limit
ActMemory Tickbox    ???
PowerSupply...
Source List Box   The power supply can be specified via Menu Command View - Power Supplies, depending on the option selected on the Power Supply page, the power can be on/off. This can be used to trip valves if required.
Available Default   Returns the status of the power supply.
Load...
PowerFactor Input   The power factor used to estimate the shaft power.
ShaftPower Input   Estimates the ShaftPower based on the Power Factor and flow through the valve.

Adding this Model to a Project

Insert into Configuration file

Sort either by DLL or Group.

 

DLL:

Piping1.dll

Units/Links

Piping: Valve(1)

or

Group:

Mass Transfer

Units/Links

Piping: Valve(1)

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


Insert into Project

 

Insert Unit

Piping

Valve(1)

See Insert Unit for general information on inserting units.