Module 4 - Logical Operations

Supported by:

Aspen HYSYS Training

Module 4: Logical Operations

Tutor: M. Ersharry Yunashtanto

Zayyanatun Zulfa Ikha Muliawati Mada Harahap

• The Set Operation • The Adjust Operation • The Balance Operation

• The Recycle Operation

• The Spreadsheet

Logical Operations Used in HYSYS Steady State

SET OPERATION

• Function : used to set the value of specific Process Variable (PV)

in relation to another PV.

• The set operation only can be used to define relationship between the same PV in two like objects,

i.e.: relationship between two temperatures of two different streams.

• The dependent, or target variable is defined in terms of

independent, or source variable according to the following linear relation:

Set Operation

Y = MX + B

where: Y = Dependent (target) variable X = Independent (source) variable M = Multiplier (slope) B = Offset (intercept)

How to Add Set Operation (1st method)

How to Add Set Operation (2nd method)

click

Double click

Example Using Set in Simulation

Set Connections Tab

Click to choose Target Object and variable to set

Click to choose Source Object where independent variable placed

Set Parameters Tab

Define Multiplier and offset for dependent variable towards independent variable

ADJUST OPERATION

• Function : varies the value of one stream variable (the independent

variable) to meet a required value or specification (the dependent variable) in another stream or operation (automatically conduct the trial and error iterations.)

• Unlike set operation, Adjust can be used for both different and same Process Variable in two different objects.

Adjust Operation

How to Add Adjust Operation (1st method)

How to Add Adjust Operation (2nd method)

click

Double click

Example Using Adjust in Simulation

Adjusting feed temperature to get specific molar flow rate in SepLiq.

Adjust Connections Tab

Click to choose object and variable that want to be adjusted

Click to choose target object and variable

Type the specified target value

User can input specific target value, or choose the value from another object with the same process variable

Adjust ParametersTab

Define convergence criteria on this tab. Method: Broyden: used this to quickly converge to the desired value Secant: generally results in good convergence once the solution has been bracketed Tolerance: The maximum difference between the Target Variable and the Target Value Step Size: The initial step size employed until the solution is bracketed Minimum/Maximum: The upper and lower bounds for the independent variable (optional) are set in this field Maximum Iterations: The number of iterations before HYSYS quits calculations

SET & ADJUST OPERATION EXERCISE

Problem Description: There are two wells (A and B) with different composition that want to be joined. Well temperature and pressure are 120oC and 40 barg. A : B Molar flow ratio is 80 : 20 The expected gas flowrate from well is 300 MMSCFD And water gas ratio is 20 Sbbl/MMSCF

TARGET PFD

OPEN FILE : SET-ADJUST EXERCISE-STARTER.HSC

BALANCE OPERATION

• Function : provides a general-purpose heat and material balance

facility. • There are six Balance types which are defined in the table below:

Balance Operation

Type Definition

Mole An overall balance is performed where only the molar flow of each component is conserved.

Mass An overall balance is performed where only the mass flow is conserved.

Heat An overall balance is performed where only the heat flow is conserved.

Mole and Heat

An overall balance is performed where the heat and molar flow are conserved.

Mass and Heat

An overall balance is performed where the overall mass flow and heat flow are conserved.

General HYSYS will solve a set of n unknowns in the n equations developed from the streams attached to the operation. Component ratios may be specified on a mole, mass or liquid volume basis.

How to Add Balance Operation (1st method)

How to Add Balance Operation (2nd method)

click

Double click

Example Using Balance in Simulation

create a stream that has the same molar composition and flow rate as another stream, but a different pressure and temperature (e.g. - at dew point conditions)

Example Using Balance in Simulation

all the components of gas stream RX Inlet are converted to pure propane in the outlet stream RX Outlet at the same pressure condition. Determine the temperature of RX Outlet when there is no accumulation happen. Mass in = Mass out

Balance Connections Tab

Click to choose inlet stream

Click to choose outlet stream

Balance Parameters Tab

Click to choose balance type

Balance Worksheet Tab

Mass Flow for each stream is the same

Temperature of RX Outlet

BALANCE OPERATION EXERCISE

Problem Description: Create a stream that has the same molar composition and flow rate as another stream, but a different pressure and temperature (e.g. - at dew point conditions). dewpoint of the product at 6000 kPa.

TARGET PFD

OPEN FILE : BALANCE EXERCISE-STARTER.HSC

RECYCLE OPERATION

• Use this operation every time you need to recycle a stream.

• The logical block connects the two streams around the tear stream

(stream with temporary specification).

• Before you can install the RECYCLE the flowsheet must have completed. That means there need to be values for both the assumed stream and the calculated stream.

• Once the Recycle is attached and running, HYSYS compares the two values, adjusts the assumed stream, and runs the flowsheet again. HYSYS repeats this process until the two streams match within specified tolerances.

Recycle Operation

How to Add Recycle Operation (1st method)

How to Add Recycle Operation (2nd method)

click

Double click

Example Using Recycle in Simulation

Recycle Connections Tab

Click to choose inlet stream

Click to choose outlet stream

Inlet stream will always be a product stream from a unit operation.

Outlet stream will always be a feed stream to a unit operation

Recycle Parameters Tab

to set the convergence criteria factor for each of the variables listed

to select the transfer direction of the variable

RECYCLE OPERATION EXERCISE

Problem Description: a two-phase feed stream (FEED) is mixed with a recycled stream (RECYCLE) and fed to separator V-100. The vapour from V-100 is expanded in expander E-100 and then reflashed in separator V-101. Half of the liquid from this separator is fed to pump P-100 and then recycled back and mixed with the fresh feed.

TARGET PFD

OPEN FILE : RECYCLE EXERCISE-STARTER.HSC

SPREADSHEET

• The Spreadsheet applies the functionality of Spreadsheet programs

to flowsheet modeling. With essentially complete access to all process variables, the Spreadsheet is extremely powerful and has many applications in HYSYS.

• The HYSYS SPREADSHEET has standard row/column functionality. You can import a variable, or enter a number or formula anywhere in the spreadsheet.

• Complex mathematical formulas can be created, using syntax which is similar to conventional Spreadsheets. Arithmetic, logarithmic, and trigonometric functions are examples of the mathematical functionality available in the Spreadsheet.

Spreadsheet

How to Add Spreadsheet (1st method)

How to Add Spreadsheet (2nd method)

click

Double click

Example Using Spreadsheet in Simulation

Spreadsheet Connections Tab

Used to Add, Delete and Edit Imported and Exported variable

Spreadsheet Parameters Tab

Used to edit number of column and rows on the spreadsheet

Show cells that contain calculated results form formulas define on the spreadsheet

Spreadsheet Formulas Tab

Show the results of the calculation

Show Formulas used for calculation

Spreadsheet Tab

Color Code: Blue: Show independent value imported from stream in the simulation or value/text that we manually type on the spreadsheet. Black: Show dependent value imported from stream in the simulation. Red: Show cell that contain formulas

How to Import Data to Spreadsheet Tab (1st Method)

1. On the spreadsheet cell, right click the mouse and then choose import variable

2. Select variable to be import

3. Click OK

How to Import Data to Spreadsheet Tab (2nd Method)

1. Open stream that want to be imported to spreadsheet

2. Right click on the variable that want to imported. HOLD the right click.

3. Drag the mouse to desired cell. RELEASE the right click

How to Import Data to Spreadsheet Tab (3rd Method)

Select targeted cell

SPREADSHEET EXERCISE

From fluid composition described in the feed stream and following information, calculate reynold’s number of the liquid. Pipe ID : 0.02 m

TARGET SPREADSHEET

OPEN FILE : SPREADSHEET-STARTER.HSC

Re = Reynold number, dimensionless ρ = liquid density (kg/m3) D = pipe ID (m) v = liquid flow velocity (m/s) μ = liquid viscosity (kg/m-s)

Viscosity 1cP = 0.001 kg/m-s

Thank You

M. Ersharry Yunashtanto Zayyanatun Zulfa

Ikha Muliawati Mada Harahap

• Aspen Hysys Unit Operation Guide, Aspen Technology, 2011

• HYSYS.Plant Simulation Basis, Hyprotech Ltd, 2000.

• “……………….”, Process Simulation Workshop.

REFERENCES