Non return valve

Navigation: Models ➔ Pressure Changing Models ➔ Non Return Valve

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General Description

The valve model will add pressure drop to the stream or operates at a specified pressure.

Diagram

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

The default access window consists of a number of sections,

1. Valve_NR-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.

Non Return Valve Page

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

Tag (Long/Short)	Input / Calc	Description/Calculated Variables / Options
Tag	Display	This name tag may be modified with the change tag option.
Condition	Display	OK if no errors/warnings, otherwise lists errors/warnings.
ConditionCount	Display	The current number of errors/warnings. If condition is OK, returns 0.
GeneralDescription / GenDesc	Display	This is an automatically generated description for the unit. If the user has entered text in the 'EqpDesc' field on the Info tab (see below), this will be displayed here. If this field is blank, then SysCAD will display the UnitType or SubClass.
Requirements
PressMethod	None	No pressure change across the unit.
	Drop	The user specifies a pressure drop. Therefore, Pout = Pin - Pdrop
	Fixed	The user specifies a fixed outlet pressure from the unit.
	Atmos	The outlet pressure from the unit is set to atmospheric pressure.
PressDropReqd / PDropReqd	Input	The required pressure drop. Visible if the Drop method is selected.
PressureReqd / P_Reqd	Input	The required outlet pressure. Visible if the Fixed method is selected.
VLEquilibrium	Off	Vapour Liquid Equilibrium is off.
	On	Vapour Liquid Equilibrium (VLE) is enabled. The associated section, VLE becomes visible and may be configured. Note: This option may automatically adjust the species make-up in Qo.
Results
MassFlow / Qm	Calc	The total mass of material flowing through the valve.
TemperatureIn / Ti	Calc	The temperature of material at the inlet of the valve.
TemperatureOut / To	Calc	The temperature of material at the outlet of the valve.
PressureIn / Pi	Calc	The actual pressure at the inlet of the valve.
PressChange / dP	Calc	The pressure change in the valve.
PressureOut / Po	Calc	The actual pressure at the outlet of the valve.
DensityIn / Rhoi	Calc	The density of material at the inlet of the valve.
DensityOut / Rhoo	Calc	The density of material at the outlet of the valve.
VapourFracIn / Vfi	Calc	Vapour Mass Fraction at the inlet of the valve.
VapourFracOut / Vfo	Calc	Vapour Mass Fraction at the outlet of the valve.

Adding this Model to a Project

Add to Configuration File

Sort either by DLL or Group:

	DLL:	Piping1.dll	→	Units/Links	→	Piping: Valve - Non Return(1)
or	Group:	Mass Transfer	→	Units/Links	→	Piping: Valve - Non Return(1)

See Model Selection for more information on adding models to the configuration file.

Insert into Project Flowsheet

Insert Unit

→

Piping

→

Valve - Non Return(1)

See Insert Unit for general information on inserting units.