Piping Networks in CHEMCADCHEMCAD PIPING SYSTEMS
This book will talk about:
Chapter 1-Introduction to Piping Networks in CHEMCAD
Chapter 2-UnitOps for Piping Networks
Chapter 3-Control Valve Sizing
Chapter 4-Simple Flow Example
Chapter 5-Branched Flow Example
Chapter 6-Flow Relief Piping System
Chapter 7-Piping Calculation Methods
Chapter 8-Descriptions of Valves and Fittings
CHEMCAD PIPING SYSTEMS
TABLE OF CONTENTS
Chapter 1-Introduction to Piping Networks in CHEMCAD .................................................. ....................... 1
Piping Networks.......................................... .................................................. ............................................ 1
About Piping Network Systems .................................................. .................................................. ...... 1
Flowrate as a Function of Pressure for Fluid Flow.............................................. ................................2
About Modeling Piping Network Systems........................................... ................................................ 3
Chapter 2-UnitOps for Piping Networks.......................................... .................................................. ......... 5
Pressure Node.............................................. .................................................. .......................................... 5
Flowrate Options at Node.............................................. .................................................. ............ 7
Fixed Flowrates at Node.............................................. .................................................. .............. 7
Variable Flowrates at Node .................................................. .................................................. ..... 7
Mass Balance Limitations for Flowrate Calculation .................................................. ................... 8
Node as Divider .................................................. .................................................. .................................... 9
Pressure Node Dialog Screen .................................................. .................................................. ............. 10
Mode .................................................. .................................................. .................................... 10
Pressure at Node .................................................. .................................................. .................. 11
Minimum Pressure .................................................. .................................................. ................ 11
Maximum Pressure .................................................. .................................................. ............... 11
Elevation......................................... .................................................. ........................................ 11
Flowrate Options (Inlet) .................................................. .................................................. ......... 11
Stream Number .................................................. .................................................. ..................... 11
Flowrate Option............................................ .................................................. ........................... 11
Fixed Mole Rate/Fixed Mass Rate/Fixed Volume Rate.............................................. ........ 11
Flow Set by Pipe/Valve/Pump.............................................. .............................................. 11
Free Inlet Stream............................................ .................................................. .................. 11
Use Current Stream Rate.............................................. .................................................. ... 12
Value .................................................. .................................................. .................................... 12
Flowrate Options (Outlet) .................................................. .................................................. ...... 12
Stream Number .................................................. .................................................. ..................... 12
Flowrate Option............................................ .................................................. ........................... 12
Fixed Mole Rate/Fixed Mass Rate/Fixed Volume Rate.............................................. ........ 12
Flow set by Pipe/Valve/Pump.............................................. ............................................... 12
Free Outlet Stream............................................ .................................................. ............... 12
Value .................................................. .................................................. .................................... 12
Pipe Simulator .................................................. .................................................. .................................... 12
Description .................................................. .................................................. ........................... 12
Piping Network Modes of Pipe Simulator .................................................. ................................ 13
Pump .................................................. .................................................. .................................................. 13
Description .................................................. .................................................. ........................... 13
Piping Network Modes of Pump UnitOp .................................................. .................................. 13
Valves............................................ .................................................. .................................................. ..... 13
Description .................................................. .................................................. ........................... 13
Piping Network Modes of Valve UnitOp .................................................. .................................. 14Revision May 18, 2004Control Valve............................................. .................................................. ............................................14
Description .................................................. .................................................. ............................14
Piping Network Modes of Control Valve............................................. ........................................14
Compressor........................................ .................................................. .................................................. .14
Piping Network Modes of Compressor........................................ ...............................................14
Node as Mixer .................................................. .................................................. .....................................14
Steady State UnitOps........................................... .................................................. .................................14
Chapter 3-Control Valve Sizing .................................................. .................................................. ............15
Topics Covered........................................... .................................................. ............................15
Problem Statement .................................................. .................................................. ................15
The Simulation .................................................. .................................................. .......................16
Control Valve Sizing............................................ .................................................. .....................16
Rating Case .................................................. .................................................. ...........................18
Flowrate as a Function of Pressure.......................................... .................................................. 22
Chapter 4-Simple Flow Example .................................................. .................................................. ..........27
Topics Covered........................................... .................................................. ............................27
Problem Statement .................................................. .................................................. ................27
Creating the Simulation........................................ .................................................. ...........................28
Using Controllers to Simplify the Problem........................................... ..............................................29
Calculating NPSHA.................................................. .................................................. .......................31
Chapter 5-Branched Flow Example........................................... .................................................. .............31
Topics Covered........................................... .................................................. ............................31
Problem Statement .................................................. .................................................. ................31
Creating the Simulation........................................ .................................................. ...........................32
Running the Simulation .................................................. .................................................. .................35
Selecting a Pump.............................................. .................................................. .............................35
Chapter 6-Flow Relief Piping System............................................ .................................................. .........38
Topics Covered........................................... .................................................. ............................38
Flare Header Design .................................................. .................................................. .....................38
Problem Statement .................................................. .................................................. ................39
One Branch............................................ .................................................. ........................................40
Two Branch .................................................. .................................................. ..................................40
Four Branch .................................................. .................................................. .................................41
Specifying the Outlet Pressure.......................................... .................................................. ..............43
Addition of Pipe to Discharge......................................... .................................................. .................43
Effect of Closed Valve............................................. .................................................. ........................43
Different Approaches to Relief Problems .................................................. ........................................44
Chapter 7-Piping Calculation Methods .................................................. .................................................. .44
The General Energy Equation.......................................... .................................................. ...............44
Conservation of Momentum.......................................... .................................................. ..................46
Friction Factor Determination..................................... .................................................. .....................47
Acceleration Component .................................................. .................................................. ...............48
The Isothermal Flow Equation.......................................... .................................................. ......................48
The Darcy-Weisbach Equation.......................................... .................................................. .....................49
The Hazen-Williams Equation .................................................. .................................................. ..............49
The Fritzche Equation .................................................. .................................................. ..........................49
Two Phase Flow.............................................. .................................................. ......................................50
Revision May 18, 2004Definitions for Two Phase Flow .................................................. .................................................. ........... 50
Liquid Holdup .................................................. .................................................. ........................ 50
Gas Holdup or Gas Void Fraction.......................................... .................................................. .. 50
No-Slip Liquid Holdup............................................ .................................................. .................. 50
Two-Phase Density .................................................. .................................................. ............... 51
Superficial Velocity .................................................. .................................................. ................ 51
Slip Velocity.......................................... .................................................. ......................................... 51
Modification of the Pressure Gradient Equation for Two Phase Flow.............................................. ........ 51
The Baker Method for Two Phase Flow Calculation....................................... ......................................... 52
Establishing the Two-Phase Flow Pattern........................................... ...................................... 52
Pressure Losses for Two-Phase Flow.............................................. ......................................... 53
Dispersed Flow.............................................. .................................................. .......................... 53
Bubble Flow.............................................. .................................................. .............................. 54
Slug Flow.............................................. .................................................. .................................. 54
Stratified Flow.............................................. .................................................. ........................... 54
Wave Flow.............................................. .................................................. ................................ 54
Plug Flow.............................................. .................................................. .................................. 55
Annular Flow .................................................. .................................................. ......................... 55
The Baker Method Procedure......................................... .................................................. ....................... 57
Assumptions....................................... .................................................. .................................... 57
Procedure......................................... .................................................. ...................................... 57
Two Phase Flow Regime............................................ .................................................. ............. 57
CalculateΔPv,100.................................................. .................................................. ..................... 58
Calculate Lockhart-Martinelli Parameter, X2.................................................. ............................ 58
Calculate Φ2 .................................................. .................................................. .......................... 58
Calculate ΔP2Φ,100.................................................. .................................................. ................... 59
The Beggs and Brill Method for Two Phase Flow Calculations .................................................. ............. 59
Horizontal Flow.............................................. .................................................. ................................ 60
Flow Regime Determination .................................................. .................................................. ......... 64
Two-Phase Density .................................................. .................................................. ...................... 65
Friction Factor............................................ .................................................. .................................... 66
Acceleration Term .................................................. .................................................. ........................ 67
Elevation Term .................................................. .................................................. ............................ 67
Vertical Flow.............................................. .................................................. ........................................... 68
Vertical Flow Regimes........................................... .................................................. ......................... 68
Set Up Calculations .................................................. .................................................. ............................ 70
The 3-K (Darby) Method of Specifying Flow Resistances....................................... ................................. 75
Heat Loss in Piping Systems .................................................. .................................................. ............... 76
Net Positive Suction Head.............................................. .................................................. ....................... 76
Net Positive Suction Head.............................................. .................................................. ................ 76
Pumping Saturated Liquids .................................................. .................................................. .......... 78
Pipe Sizing Using the Kent Method .................................................. .................................................. ..... 78
Variable Definitions....................................... .................................................. ........................................ 80
Revision May 18, 2004Chapter 8-Descriptions of Valves and Fittings.......................................... ................................................81
Valves .................................................. .................................................. ..........................................81
Flanged Fittings.......................................... .................................................. ....................................81
Welded Fittings .................................................. .................................................. ............................82
Miscellaneous .................................................. .................................................. ..............................82
Valve Diagrams .................................................. .................................................. ...................................83
Gate Valve .................................................. .................................................. ...................................83
Globe Seat Flat, Bevel, Plug .................................................. .................................................. .........84
Globe Wing/Pin Guided Disk.............................................. .................................................. .............85
Angle, No Obstruction .................................................. .................................................. ...................85
Angle, Wing/Pin Guided Disk .................................................. .................................................. ........86
Y-Pattern Globe 60 Degrees. .................................................. .................................................. ........86
Y-Pattern Globe 45 Degrees .................................................. .................................................. .........86
Ball Valve .................................................. .................................................. .....................................87
Butterfly, 2-8 Inches .................................................. .................................................. ......................88
Butterfly, 10-14 Inches .................................................. .................................................. ..................88
Butterfly, 14-24 Inches .................................................. .................................................. ..................88
Plug, Straight Way............................................... .................................................. ...........................89
Plug, 3-Way (Straight Run) .................................................. .................................................. ...........89
Plug, 3-Way Through Branch .................................................. .................................................. ........89
Foot Valve, Poppet Disk.............................................. .................................................. ....................90
Foot Valve, Hinged Disk.............................................. .................................................. ....................90
Swing Check, Clearway-90 .................................................. .................................................. ...........90
Swing Check, Tilting Seat .................................................. .................................................. .............90
Tilt Disk, 5 Degrees 2-8 Inches .................................................. .................................................. .....91
Tilt Disk, 5 Degrees 10-14 Inches .................................................. .................................................. .91
Tilt Disk, 5 Degrees 16-48 Inches .................................................. .................................................. .91
Tilt Disk, 15 Degrees 2-8 Inches .................................................. .................................................. ...91
Tilt Disk, 15 Degrees 10-14 Inches .................................................. .................................................9 1
Tilt Disk, 15 Degrees 16-48 Inches .................................................. .................................................9 1
Lift or Stop Check Valve, Globe .................................................. .................................................. ....91
Lift or Stop Check Valves, Angle............................................. .................................................. ........92
Flanged Fittings.......................................... .................................................. ...........................................93
Standard Elbow, 90 Degrees .................................................. .................................................. ........93
Standard Elbow, 45 Degrees .................................................. .................................................. ........93
Standard Elbow, 90 Long R .................................................. .................................................. ..........93
Return Bend, 180 Degrees, Close (Flanged) .................................................. ..................................94
Standard T, Flow-through Run (Flanged)......................................... .................................................9 4
Standard T, Flow-through Branch (Flanged)......................................... ............................................94
45 Degrees T, Flow through Run (Flanged) .................................................. ....................................95
45 Degrees T, Flow through Branch (Flanged) .................................................. ...............................95
Elbow 90 Degrees, R/D = 1.0 (For Welded, Flanged, or Screwed) .................................................. .96
Elbow 90 Degrees, R/D = 1.5 (For Welded, Flanged, or Screwed) .................................................. .96
Elbow 90 Degrees, R/D = 2.0 (For Welded, Flanged, or Screwed) .................................................. .96Revision May 18, 2004Welded Fittings.......................................... .................................................. ........................................... 96Exit from Pipe .................................................. .................................................. ................................... 100
Elbow 45 Degrees, R/D = 1.0 (Welded).......................................... .................................................. 96
Elbow 45 Degrees, R/D = 1.5 (Welded).......................................... .................................................. 96
Elbow 45 Degrees, R/D = 2.0 (Welded).......................................... .................................................. 97
Return Bend 180, R/D = 1.0 (Welded).......................................... .................................................. .. 97
Return Bend 180, R/D = 1.5 (Welded).......................................... .................................................. .. 97
Return Bend 180, R/D = 2.0 (Welded).......................................... .................................................. .. 97
Tee 100% Flow through Run (Welded) .................................................. .......................................... 97
Tee 100% Flow out Branch (Welded).......................................... .................................................. ... 97
Tee 100% Flow in Branch (Welded).......................................... .................................................. ..... 97
Reducer (Welded) .................................................. .................................................. ........................ 98
Miscellaneous..................................... .................................................. .................................................. 99
Entrance, Inward Projecting........................................ .................................................. ........................... 99
Entrance, Sharp Edged .................................................. .................................................. ....................... 99
Entrance, Slightly Rounded .................................................. .................................................. ................. 99
Entrance, Well Rounded........................................... .................................................. ............................ 99
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