aft presentation in india
DESCRIPTION
Aft Presentation in IndiaTRANSCRIPT
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AFT Products
Reinaldo Pinto Global Sales Manager
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..\Brand Video Compressed\AFT Brand Video 35MB FINAL.mp4
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Agenda
About Applied Flow Technology
Office and Worldwide Distributors
Product Applications
AFT Software List
Pipe Network Design Challenges
Pipe Network Design Challenges and AFT products
Customers
Overview of AFT Software
Fathom
Fathom Examples
Impulse
Impulse Examples
Arrow
Arrow Examples
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About Applied Flow Technology
Applied Flow Technology (AFT) is an international software development and consulting company
Founded in 1993, AFT has rapidly grown to be a leader in the pipe flow modeling software market
Primary business focus is developing high quality fluid flow analysis products for Microsoft Windows
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AFT Office and Worldwide Distributors
Representatives in 32 countries
Customers in 70+ countries
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AFT products are being successfully applied to a broad range of industrial systems: Power generation systems Chemical and petrochemical systems Oil and gas production, transportation, refining and delivery Marine and offshore Automotive systems Aerospace systems Air conditioning and refrigeration systems Semi-conductor manufacturing systems Pulp and paper processing Fire suppression Water and Wastewater treatment plant design Mining processing and support systems Biomedical products and pharmaceutical processing Municipal water distribution
September 20, 2012 6
Product Applications
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Incompressible pipe network analysis
AFT Fathom 8 AFT Fathom Add-On Modules
XTS - eXtended Time Simulation GSC - Goal Seek & Control SSL Settling Slurry simulation
According to Hatch Mott McDonald, there are many benefits of using AFT Fathom software.
AFT Fathom is, above all, reliable software. This is crucial to Hatch Mott MacDonald, a company whose reputation depends on the reliability of the final product. It is robust, and forthcoming with its calculation approaches.
AFT Fathom 8.0 Viewer (No Cost) AFT Mercury 7.0
7
Overview of AFT Software
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Compressible flow pipe network analysis AFT Arrow 5.0
In commenting on the benefits achieved by modeling this complex system with AFT Arrow, Mr. Klepacki said;
Using AFT Arrow I could check all parameters and find the optimal dimensions of conduits in order to deliver the required flow through the FGD plants. Another very important aspect is when we are to introduce changes. (in my case I have calculated about 40 scenarios so it has brought me a really great benefit).
AFT Arrow Add-On Modules GSC - Goal Seek & Control
AFT Arrow 5.0 Viewer (No Cost)
AFT Titan 4.0
8
Overview of AFT Software
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Overview of AFT Software (Cont.)
Transient Analysis
AFT Impulse 5.0
According to Chicago Bridge Iron about Impulse:
AFT Impulse allowed the separation of "reality" from "theoretical" to arrive at a true model of the existing system
AFT Impulse 5.0 Viewer (No Cost)
Chempak Property Database Property database of ~700 fluids Ability to define static pre-mixtures Dynamic mixing capability in Arrow
9
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Overview of AFT Software (Cont.)
AFT Academic Program
Licenses for Research and Development
Licenses for Hydraulic Courses
AFT Flow Expert Package (New)
AFT Flow Expert Packages provide consulting services
beyond typical technical support requests on the installation,
upgrade assistance, and functionality of AFT software
Package Options
5 Hours
10 Hours
20 Hours
10
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Pipe Network Design Challenges
1. Meeting design parameters Specs.: Pressure, Flow, Temperature, Energy Consumption, etc. 2. Dealing with Hydraulic Phenomena's:
1. Cavitation (steady state and transient)
Valves erosion Pumps erosion Valves leak Pipe Collapse ..\..\Seminar\Technical Topics\Collapse\Railroad tank car vacuum implosion.avi Pipe flashing (vapor cavities)
2. Overpressures
Pipe Rupture ..\..\Seminar\Technical Topics\Pipe failure - pump start-up\Sea Water Pump Explosion _ Video _ Break.com_2.mp4
Pipe Support Failure Waterhammer Videos\How a Bladder Surge Tank can alleviate column separation1.wmv ;
In the construction of pump storage installation the greatest concern must be given to the question of operational safety right from the beginning. For this reason exhaustive and accurate data on the pressure fluctuations caused when the pump motors cut out suddenly must be worked out in the project stage. Only this way suitable precautions be taken in good time to prevent inadmissible pressures M. Marchal, G. Flesh and P. Suter
Article: The calculation of Waterhammer problems by means of the digit computer
System Protection devices Failure to Control: Relief Systems, Equipment Protection devices, etc. Relief Valve Cycling (Chattering) ..\..\Seminar\Technical Topics\Valve Chattering\Safety Valve -
Chattering.avi
3. Sonic Choking Flow limitation
3. Code Compliance
11
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Pipe Network Design Challenges and AFT
products
AFT products will not only allow you to deal with all the Pipe Network Design Challenges , also they will give you access to powerful designing tools that will make your design more easy, comprehensive and facilitates finding a solution to any problem. Among these tools we can mention:
Scenario Manager to track all design variants and operational possibilities in a single model file.
Detailed modeling for centrifugal and positive displacement pumps Thermal analysis including piping heat transfer and heat exchanger
modeling
Pump vs. system curve generation including individual head curves and composite efficiency
Select pumps from online manufacturer catalogs Specify alerts that automatically highlight output values that are out of
range for flow, pressure or velocity
Built-in library of fluids and fittings Supports Newtonian and non-Newtonian fluids, including non-settling
and settling slurries
12
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Customers
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Customers in India
14
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AFT Fathom 8 Overview
Models incompressible network pipe systems Liquid and low velocity gas systems
Implements highly advanced Microsoft Windows graphical interface Users give Fathom high marks for ease of use
Models open and closed systems Models systems that are pressure, gravity or pump driven Models heat transfer and system energy balance Offers broad range of innovative reporting features
Printed output is of report quality
Offers customizable component and property databases Cost calculations
Rheological data handling to support non-Newtonian fluids
Modules for: Extended Time Simulation Goal Seek & Control Settling Slurries
15
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AFT Fathom Add-On Module Overview
XTS Simulate dynamic behavior of systems over time
Models infinite and open and closed finite tanks of constant and varying cross section
Supports user defined time and event transients of pumps, valves and other components
GSC Automatically determines input variables that will yield specified
output values
Extends Fathoms control simulation capabilities to include remote sensing
SSL Simulates settling slurry behavior
Simulates pump performance degradation
16
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AFT Impulse 5.0 Overview
Models Transient flow in pipe networks Implements highly advanced Microsoft Windows graphical interface Models system transients caused by
Sudden valve closures Pump startups and shutdowns including pump inertia effects Relief valve cracking Events defined within the system (e.g. flow, pressure, etc.)
Includes modeling of Control and relief valves Pumps Accumulators & surge tanks Vacuum relief valves
Models open and closed systems Includes a steady-state solver to determine initial conditions
Can also import AFT Fathom models
Calculates unbalanced transient forces Forces can be graphed or exported as Force/Time data files
17
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Mercury 7.0 Overview
Allows: Analysis, design and optimization of incompressible network pipe systems
Combines a powerful hydraulic solver and flexible graphical interface with an advanced optimization engine
Automatically selects optimal pipe and component sizes to minimize initial or life cycle cost, size or weight
Ability to apply multiple constraints to pipes and junctions
Cost optimization may include; non-recurring costs (materials and installation)
recurring costs (energy and maintenance) including time varying cost (energy costs varying with time)
Offers customizable engineering and cost databases
Includes powerful modeling and output capabilities of AFT Fathom 7.0
September 20, 2012 18
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Arrow 5.0 Overview
Models compressible network pipe systems
High to low velocity gas systems High to low pressures
Implements highly advanced graphical interface very similar to Fathom
Models open and closed systems Accurately models
Real gases Heat transfer Highly compressible (sonic and near sonic) systems
Offers broad range of innovative reporting features Balances flow and energy throughout the system Offers customizable component and property databases Includes high accuracy steam/water properties to ASME Modules for:
Goal Seek & Control Cost calculations
19
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Arrow Add-On Module Overview
GSC
Automatically determines input variables that will yield specified output values
Extends Arrows control simulation capabilities to include remote sensing
CST
Supports cost databases for piping, fittings, valves, pumps and other system components
Analyzes first and life cycle cost of piping/pump systems
Integrates system hydraulic design and cost
20
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Titan 5.0 Overview
Allows: Analysis, design and optimization of compressible network pipe systems
Combines a powerful hydraulic solver and flexible graphical interface with an advanced optimization engine
Automatically selects optimal pipe and component sizes to minimize initial or life cycle cost, size or weight
Ability to apply multiple constraints to pipes and junctions
Cost optimization may include; non-recurring costs (materials and installation)
recurring costs (energy and maintenance) including time varying cost (energy costs varying with time)
Offers customizable engineering and cost databases
Includes powerful modeling and output capabilities of AFT Arrow 4.0
21
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AFT FATHOM
Modelaje de Flujo Incompresible
22
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General purpose pipe network incompressible flow analysis
Advanced drag-and-drop interface
Calculates pressure drop, flow distribution and (optionally) energy balance in pipe networks
Implements Newton-Raphson matrix techniques to solve 3 equations:
Continuity (Mass) Equation
Momentum (Bernoulli) Equation
Energy Equation (optional)
23
AFT Fathom General Description
AFT Fathom -
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Can model systems in any generalized configuration
Open or closed systems
Branching systems
Looping systems
Can model any fluid in which the viscosity is Newtonian
Can model non-Newtonian fluids using Power Law and Bingham Plastic
Can model variable fluid properties
English and SI units supported
24
AFT Fathom General Description (cont.)
AFT Fathom -
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Branching section (up to 25 pipes)
Known pressure or flow boundaries
Pumps
Pump curves follow a polynomial equation or can be linearly interpolated
Centrifugal pumps and positive displacement pumps
Pressure and flow control valves
Relief valves and check valves
Spray discharge nozzles, sprinklers.
Heat Exchangers
Tanks
25
Components That Can Be Modeled
AFT Fathom -
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Heat exchangers
Hydraulic losses
Heat transfer
General fittings and components where the resistance curve follows a polynomial relationship
Also can be modeled as linearly interpolated data
Piping insulation
26
Components That Can Be Modeled (cont.)
AFT Fathom -
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AFT Fathom uses the Newton-Raphson Method to solve the flow distribution in a pipe network
The Newton-Raphson Method for pipe networks is a matrix method
This method gained favor with the introduction of the digital computer
The technique has been considered standard industry practice for 40 years
27
Solution Techniques
AFT Fathom -
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Mass Conservation
=
Momentum Equation (Bernoulli)
1 +1
21
2 + 1 = 2 +1
22
2 + 2 +
The dynamic pressure and static pressure can be combined into the stagnation (total) pressure, and the solution is then for
total pressure
Therefore, the momentum equation becomes
,1 + 1 = ,2 + 2 +
28
Basic Laws of Pipe Flow
AFT Fathom -
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Traditional method of friction loss calculation uses the Darcy-Weisbach friction factor, f
=
1
22
The friction factor is not a constant, but a function of the pipe wall characteristics and the Reynolds number
AFT Fathom uses the iterative Colebrook-White correlation for turbulent flow and the traditional laminar flow equation
= 1.14 2 log
+
9.35
2
(Re > 4000)
=64
(Re < 2300)
29
Law of Friction
AFT Fathom -
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AFT FATHOM
EXAMPLES
Modelaje de Flujo Incompresible
30
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Determine the pump head and power for the following system
Water system at 21 degrees C
Reservoir at 3 meters elevation needs to be pumped up a hill to a reservoir at 60 meters elevation
Flow requirement is 110 m3/hr
The total pipe length is 300 meters
The pipe is 4 inch (10.23 cm ID) Schedule 40 Steel
Pump efficiency = 80%
31
Model 1: Pump Sizing
5m
295m
3m
3m
60m
AFT Fathom -
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32
Model 1: Pump Sizing - Layout
AFT Fathom -
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33
Model 1: Pump Sizing - Output
Note: Pump Head Rise = 93.4 m
This has 2 parts: Elevation Rise = 57.0 m Frictional Head = 36.4 m
AFT Fathom -
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34
Model 1: Pump Sizing Select a Pump
Choose a pump with adequate head rise at the design flow Q dH (m3/h) (m) 0 102 110 94 220 56
AFT Fathom -
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35
Model 1: Pump Sizing Enter Pump Data
AFT Fathom -
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36
Model 1: Pump Sizing Fit Curve to Data
AFT Fathom -
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37
Model 1: Pump Sizing Review Selected Pump
AFT Fathom -
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38
Model 1: Pump Sizing Create Pump System Curve
AFT Fathom -
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39
Model 1- Pump Sizing System Curve H
ead
Flowrate
Total Dynamic Head (TDH)
Friction
Pump Curve
System Curve
Operating Flow Rate
Static
Hs
Hf
93.9m
57.0m
36.9m
110.7 m3/hr
AFT Fathom -
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After selecting and buying the pump in Example #1, it is determined the velocity is too high
A variable speed drive is proposed to reduce the flow rate from 110 to 90 m3/hr
What is the new efficiency and power usage?
What speed will the pump operate?
40
Model 2: Variable Speed Pumping
5m
295m
3m
3m
60m
AFT Fathom -
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41
Model 2: Variable Speed Pump Enter Setpoint
AFT Fathom -
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42
Model 2: Variable Speed Pump Output
AFT Fathom -
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43
Model 2: Variable Speed Pump New Head Rise
Note: Pump Head Rise = 81.7 m
This has 2 parts: Elevation Rise = 57.0 m Frictional Head = 24.7 m
AFT Fathom -
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44
Model 2: Variable Speed Pump Pump System Curve
Head
Flowrate
Pump Curve (No Control) System Curve
No Control
VFD VFD
Hs
Hf
Hs
Hf
No Control
Pump Curve (VFD at 92.1% Speed) 93.9m
57.0m
36.9m
110.7 m3/hr
81.7m
24.7m
90 m3/hr
57.0m
AFT Fathom -
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After selecting and buying the pump in Example #1, it is determined the velocity is too high
Use a flow control valve to reduce the flow rate from 110 to 90 m3/hr
What is the new efficiency and power usage?
What speed will the pump operate?
45
Model 3: Flow Control Valve Evaluation
5m
295m
3m
3m
60m
AFT Fathom -
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Use SHIFT key and then drag a Control Valve junction onto P2
This is the Split Pipe feature
March 14-15, 2013 46
Model 3: Flow Control Valve Add Valve
AFT Fathom -
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47
Model 3: Flow Control Valve Enter Setpoint
AFT Fathom -
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48
Model 3: Flow Control Valve Output
This has 3 parts: Elevation Rise = 57.0 m Frictional Head = 24.7 m Head Loss Across Control Valve = 16.0 m (shown on Valve Summary tab)
Note: Pump Head Rise = 97.7 m
AFT Fathom -
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49
Model 3: Flow Control Valve Pump System Curve
Head
Flowrate
Pump Curve
System Curve
Hs
Hf
Hs
Hf
Hcv
With Valve
Without Valve
Head Loss Across Control Valve
93.9m
57.0m
36.9m
97.7m
57.0m
16.0m
24.7m
110.7 m3/hr 90 m3/hr
AFT Fathom -
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Modeling and Selecting Pumps
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Pumps
Pumps can be modeled with pump curves, fixed flows or fixed pressure/head rise
Pump curves introduce a strong non-linearity into the model
Multiple pumps in parallel frequently require lower flow rate relaxation values
The pump pressure/head is listed in the General Results section of the output
Using undersized or oversized pumps can lead to modeling results that do not reflect reality
In the case of an undersized pump with hydrostatic head greater than shut off, Fathom will model backflow with the pump at shut off head
where, in reality, the pump head will be different
An oversized pump may be at runout, which is not modeled (Fathom extrapolates based on the curve fit - you can specify an end of curve
flow rate so Fathom will warn you if the solution is beyond the rate of
flow)
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Pumps
Variable speed pumps can be modeled by entering the pump speed
Pump runout can be indentified
Viscosity corrections using Hydraulics Institute Standard can be applied
Control to a flow rate, suction or discharge pressure can be performed
Variable NPSH curves can be entered
Efficiency/power data can be entered
Fathom will determine power usage and proximity to BEP
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Working with Pump Data and Results
Pump data can be entered
for the head curve, NPSH
and efficiency. Data is
input in the Pump
Configuration window.
The Pump Summary is
included in the General
Results of the Output
window
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Pump Summary
The Pump Summary report in the output window gathers all pump data into one location for convenient review
Pump head and pressure rise
Pump horsepower - ideal if no efficiency curve data is provided or brake horsepower if efficiency curve is provided
Pump speed
NPSHA and NPSHR
BEP and percent of BEP (if efficiency or power data is entered)
Viscosity correction constants CQ and CH (only if viscosity corrections are used)
This report is displayed by selection within the General Output tab of the Output Control window then accessed using the Pump Summary tab of the Output window.
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Variable Speed Pumps
If a speed other than 100% is entered for a pump, AFT Fathom will modify the pump curve according to the pump
affinity laws
Head ratio is related to speed ratio by square law
Flow ratio is related to speed ratio linearly
D
D
H
H
n
n
1
2
1
2
2
=
Q
Q
n
n
1
2
1
2
=
D
D D
D
D
H a bQ cQ dQ eQ
H s H s a s s cQ s dQ s eQ
H s a s
Q
s c s
s d s e Q
s
H s a sbQ cQ d Q
s e
Q
s
1 1 1 2
1 3
1 4
2 2
1 2 2
1 2
1 2 2
1 3 2
1
4
2 2 2 2
3 2 2
4
2 2
2 2 2 2
3 3 2
4
= + + +
= = + + +
= +
+
+
= + + + +
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Variable Speed Pumps (cont.)
For several speed ratios the pump curves look as follows:
0
5
10
15
20
0 50 100 150 200
Flow Rate (gpm)
Head
(ft)
100%
80%
60%
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Variable Speed Pumps (cont.)
For variable speed pumps Fathom can calculate the speed required to deliver a specified discharge pressure/head or flow
You cannot simultaneously input the speed because that is what is being calculated
Fathom disables the speed input field
The required speed is display in the Pump Summary of the Output window
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Variable Speed Pumps Example
Open "Variable Speed Pumps.fth" from disk (or "Variable Speed Pumps (SI).fth for metric) Models\Fathom Models\Variable Speed Pumps (SI)(complete).fth
Create a new scenario and make it current.
Set pump J7 to Controlled Pump (Variable Speed) 400 gpm / 100 m3/hr
How do the pump flows compare to the Base Scenario?
Create a new scenario below the scenario created above
Set pump J4 to 90% speed
How do the pump flow compare to the previous scenario? Why?
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Cavitation and NPSH
AFT Fathom will calculate local static pressures for the purpose of identifying cavitation
The vapor pressure of the fluid must be entered into System Properties
The Restricted Area must be input for the junction so AFT Fathom can perform the local pressure calculation
AFT Fathom does not model cavitation - rather, it identifies where it occurs in the system
If NPSH data is entered for a pump, AFT Fathom will check the required NPSH (i.e., NPSHR) vs. that which is available
(i.e., NPSHA)
NPSHA and NPSHR are displayed in the Pump Summary
AFT Fathom models variable NPSH curves
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Pump Configurations
Pump data can be entered for multiple configurations
The default is a single configuration.
A pump configuration is a pump with a specific impeller trim and operating speed
Multiple impeller trims and operating speeds can be specified as part of the pump, then a particular combination can be chosen
Data for NPSH and Efficiency (or Power) is optional
These parameters do not affect the solution
They are used only for diagnostics
With Efficiency/Power data, Fathom determines the Best Efficiency Point (BEP) and the proximity of the operating point to BEP
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Pump Configurations (cont.)
The Pump Configuration window is opened from the Pump Properties window
Click the Create button to input a new configuration
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Pump Configurations (cont.)
Multiple configurations are displayed on the Pump Properties window in dropdown lists for selection
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Pump Configurations Reference Density
Pump curves in terms of head and volumetric flow rate DO NOT change with density
Curves in terms of pressure or mass flow rate ARE dependent on density
Power curves DO change with density
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Pump Configurations Reference Density
A reference density can be entered so the difference between the system properties fluid density and the pump test fluid
(reference density) will always be accounted for
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Pump Impeller Modifications
Users can input impeller modifications
Pumps curves (and NPSH and efficiency/power curves) will be automatically adjusted
Impeller modification can be of two types:
Ratio from a single curve
Entered as percent
Interpolation between two curves
Entered as absolute diameter
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Pump Impeller Modifications (cont.)
Entering "Ratio as Percent" will use affinity laws for impellers to adjust the selected pump curve data
This feature is available whenever a pump curve is entered
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Pump Impeller Modifications (cont.)
Entering "Actual Impeller Trim" will interpolate between the closest impeller data
Affinity laws are used in the interpolation
This feature only available with multiple configurations
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Pump Impeller Information in Output
Pump Summary in Output window can show impeller information
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One Pump Can Represent Multiple Pumps
A single pump can represent multiple identical pumps in parallel or series
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Control Valves
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Control Valves
AFT Fathom has four types of control valves
Flow Control
Pressure reducing (control on downstream of valve)
Pressure sustaining (control on upstream of valve)
Pressure drop control (same pressure drop always)
Control Valve junctions can be used to model actual control valves or to size regular valves
Required pressure drop will be identified
FCV's, PRV's a PSV's will take as much pressure drop as is required to control to desired conditions
The Valve Summary in Output window shows Cv and all relevant data for Control Valves grouped together
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Supply Tank Pump Tee (Simple) Elbow (Standard)
FCV FCV
Receiver Tank
Valve (Lossless)
Pumped System with FCVs
Size pump with flow control valves (TEST7 (SI).FTH / Test 7)
Supply tank liquid elevation is 1.5 meters, with 0.7 barG (70 kPa-g) surface pressure
Receiving tank liquid elevation is at 3 meters, with 2.1 barG (210 kPa-g) surface pressure
Specify pump as Volumetric Fixed Flow at 50 m3/hr
System fluid: Water @ 21 C
All pipes are:
Steel - ANSI, 2 inch (5.25 cm ID), schedule 40
6 meters long
All non-reservoir junctions are on the ground at 0 meters elevation
Two flow control valves in parallel require 25 m3/hr each with a minimum of 0.3 bar (30 kPa) drop
System looks as below:
-
Pump
(modeled as fixed
flow)
Tee (Simple)
Elbow (Standard)
FCV FCV
Valve (Lossless)
Pumped System with FCVs (cont.)
When you try to run this model the reference pressure error is displayed The error message identifies the following junctions as lacking a reference
pressure -
This represents the following portion of the system, which is bounded by
fixed flows - the fixed flow pump and the two flow control valves
-
Pumped System with FCVs (cont.)
This is analogous to a single pipe with specified flow, Q, at the inlet and outlet -
This situation cannot be solved because there is no unique solution You could calculate the pressure drop along this pipe, but not the pressure since
a deltaP can be the difference between an infinite number of possible Pinlet and Poutlet values
This is not merely a matter of mathematics, but is an issue with real systems and is why, for example, closed loop systems have expansion or head tanks
The solution to this modeling dilemma is to make one of the FCVs a PDCV PDCV setting is the minimum deltaP needed across the control valve To insure all control valves have at least the minimum deltaP, the hydraulically
most distant FCV is selected to be changed to a PDCV
Note that the GSC module offers a direct way of solving this issue without resorting to the PDCV (see GSC Example scenario in model file)
Q Q
-
Pumped System with FCVs (cont.)
Enter a pump curve based on size requirements
TEST7 (SI).FTH / Test 7a
Data is:
40 meters at 0 m3/hr
38 meters at 50 m3/hr
30 meters at 100 m3/hr
Data is already setup in a file
Import from file PUMP7A (SI).DAT
Change control valve from PDCV to FCV
-
Pumped System with FCVs (cont.)
Add 0.7 bar (70 kPa) pressure drop to valve after pump TEST7 (SI).FTH / Test 7B)
Review failure states of FCVs
Hint:
Morph the stop valve after the pump by dragging a control valve on top of it while holding down the CTRL key, then set as PDCV at 0.7 bar
Supply Tank Pump Tee (Simple) Elbow (Standard)
FCV FCV
Receiver Tank
Valve
-
Control Valve Can't Achieve Setpoint
Control valves (flow or pressure) can end up in a situation where they cannot control to the desired control setpoint
This indicates the desired control point cannot be obtained unless the valve acts like a pump
There are three actions to not achieving the setpoint:
Always Control (Never Fail) - add pressure if required (default)
Go to the valves full open state
Close the valve
In applications with multiple flow control valves in parallel, multiple valves may not achieve the setpoint simultaneously
Any control valve that cannot control to its setpoint will go to its "action if setpoint not achievable"
Once this action is taken, it will not return to its control capability
-
Control Valve Can't Achieve Setpoint (cont.)
When control valves fail, AFT Fathom will set failed valves to their failure position and re-run the model to determine if the remaining control valves can now control
Consider a system with three FCVs in parallel, specified to fail open if there is insufficient upstream pressure
With all three controlling, the system flow and corresponding upstream pressure drop may result in insufficient pressure for some, or all, of the valves to control.
Fathom initially runs the model with the valves in the never fail mode. Failed valves will have added pressure. The valve adding the greatest magnitude of added pressure will be set to the fail open mode specified and the model re-run.
This process will continue until no valves are adding pressure, thus determining the combination of valves that may operate at their setpoint.
-
Control Valve Can't Achieve Setpoint (cont.)
Pressure control valves can lose control for two reasons:
Insufficient upstream pressure
Excessive downstream pressure
The user can assign different actions for each of these cases
-
Heat Loss in a Pipe
-
Calculate heat transfer in a pipe
Fluid is water at 65 degrees
Heat transfer is enabled when specifying the fluid
81
Model 4: Heat Loss in a Pipe
AFT Fathom -
-
Define the model components Inlet stagnation pressure is 3.5 bar
Inlet temperature is 65 degrees C
Flow is 4.5 kg/sec
All elevations are zero
82
Model 4: Heat Loss in a Pipe (cont.)
AFT Fathom -
-
Pipe properties Length is 150 meters
Steel 4 inch (9.72 cm ID) Schedule 80
Add insulation to the pipe Ambient temperature is 10 degrees C
There is one layer of insulation 3 cm thick with a thermal conductivity of 3.5 W/m-K
External convection coefficient is 60 W/m^2-K
Fluid internal convection coefficient is calculated by Fathom using a correlation, and the pipe wall resistance is calculated using the material database
Models\Fathom Models\Heat Transfer.fth
83
Model 4: Heat Loss in a Pipe (cont.)
AFT Fathom -
-
84
Model 4: Heat Loss in a Pipe (cont.)
AFT Fathom -
-
Specify Heat Rate and Inlet/Outlet Temperatures in the output
Remove head terms (like dH in pipes)
85
Model 4: Heat Loss in a Pipe (cont.)
AFT Fathom -
-
Specify insulation temperatures in the output
This is done on the Heat Transfer tab
86
Model 4: Heat Loss in a Pipe (cont.)
AFT Fathom -
-
What is the exit temperature (deg. C)?
What is the Heat loss (kW)?
87
Model 4: Heat Loss in a Pipe - Output
AFT Fathom -
-
What is the maximum insulation surface temperature (found on the Heat Transfer tab)?
88
Model 4: Heat Loss in a Pipe Output
AFT Fathom -
-
Heat Exchanger Modeling
-
Heat Exchanger
In AFT Fathom heat exchangers can be modeled: as hydraulic only (e.g., a constant property model), or
as hydraulic and thermal
AFT Fathom uses the effectiveness-NTU method based on the heat exchanger geometry chosen
Alternatively, users can - specify a constant heat rate to or from the heat exchanger
specify a heat rate which is a function of temperature
specify the exit temperature of the heat exchanger, and let Fathom determine the amount of heat transfer that results
specify the temperature or enthalpy change
The assigned heat rate and assigned exit temperature are useful for sizing heat exchangers
90
-
Heat Exchangers Tube Model
Heat exchangers have a special pressure loss model called Tube Configuration
Pressure loss is calculated based on tubes, passes, scaling, etc.
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Heat Exchanger Thermal Linking
A heat exchanger can be thermally linked to another heat exchanger
This can represent the hot and cold side of a single heat exchanger, with separate fluid loops
Models\Fathom Models\Turbine Cooling.fth
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Heat Exchanger Thermal Linking
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Scenario Manager
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Scenario Manager
The Scenario Manager allows you to keep variants of a model all with the same model
When changes are made to the base model, they are automatically passed downward
Changes at lower levels do not pass upwards
Current Workspace
scenario
Scenario tree
Create a new
scenario by clicking
here
Rename, delete, clone,
promote & save
scenarios by clicking
here
Notes can be added
for each Scenario
-
Quick Access Panel
The Quick Access Panel provides convenient utilization of all of the features of the Scenario Manager.
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Types Of Changes
The types of changes that can be made are very broad
Junctions can be turned on and off to evaluate different operating conditions
Pipe and junction data can be varied to parametrically evaluate competing designs
You can build an existing system as your base model then add to the system to evaluate expansion possibilities on the existing
system
You can easily evaluate different working fluids by setting them up as different children scenarios
You can compare a newly-built clean system to one that has been in service for a period of time with worn/corroded pipes,
etc.
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Data Propagation
Changes to ancestors propagate to all descendants if the descendant data has not been modified
Changes to descendents never propagates to ancestors
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Data Propagation (cont.)
Base
Child #1
Gr. Child #1
Diameter
3
__
__
Length
25
__
__
For many users, it is easiest to grasp Scenario Manager when it is explained
how the coding logic is actually
implemented
Blank fields for children, grandchildren, etc., mean to look to the parent for the
data If the parent is blank, then look to the
grandparent
The Base Scenario never has blank fields
Here Child #1 does not have a blank field, so its Diameter would be 2, not 3
Gr. Child #1 would have a Diameter of 2 Both still have Lengths of 25
Base
Child #1
Gr. Child #1
Diameter
3
2
__
Length
25
__
__
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Data Propagation (cont.)
Changing the Base Scenario Diameter from 3 to 6 would not impact
Child #1 or any descendents in that
line
Changing the Length from 25 to 40 would also change the length in Child
#1, Gr. Child #1, and any
descendents of Gr. Child #1
Base
Child #1
Gr. Child #1
Diameter
3
2
__
Length
25
__
__
Base
Child #1
Gr. Child #1
Diameter
6
2
__
Length
40
__
__
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Data Propagation (cont.)
Even if the Gr. Child #1 has the same Diameter as the Base, it is not
linked to the Base because it and its
parent are not blank Any change to the Base Diameter would
not affect any descendent because Child
#1 is not blank
If the Diameter in Child #1 is changed to be the same as the
Base, it will be blanked out the next time the scenario is loaded
And so will Gr. Child #1, if its Diameter is also the same
Base
Child #1
Gr. Child #1
Diameter
3
2
3
Length
25
__
__
Base
Child #1
Gr. Child #1
Diameter
3
3
3
Length
25
__
__
Base
Child #1
Gr. Child #1
Diameter
3
__
__
Length
25
__
__
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Data Propagation (cont.)
Here, Child #1 would have the following:
Diameter = 2
Length = 25
Changes to Base Diameter will not affect Diameter
Changes to Base Length will affect Length
Here, Gr. Child #1 would have the following:
Diameter = 2
Length = 15
Changes to Base Diameter will not affect Diameter
Changes to Child #1 Diameter will affect Diameter
Changes to Base Length or Child #1 Length will not affect Length
Base
Child #1
Gr. Child #1
Diameter
3
2
__
Length
25
__
15
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Ancestral Data
Ancestral source of data can be viewed for all pipes and junctions in Model Data
Scenario data can be colored for
easier viewing
Scenario names shown at left
Parameters which change are
highlighted
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Links to Parent
A link to a parent may be re-established by returning the attribute to the same value as that of its parent
This can be done manually be entering the value or selecting Same As Parent from within a pipe or junction Property window,
Solution Control or System Properties.
Links are identified by comparing attribute values on a pipe or junction number by number basis.
This means that renumbering a scenario will break all links with its parent (since numbers must be unique)
-
You can make a pipe have the same attribute as its parent by choosing Copy Data From Pipe: Parent Pipe Data
Junctions function similarly
Links to Parent (cont.)
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Example Model
A piping system will be used to transport liquid methane, propane, and ethane at cryogenic conditions
Supply is at -100 deg. C
The system will supply only one tank at a time
Pipe is Stainless Steel ANSI schedule 40S and is very well insulated (no heat transfer)
Supply is pressurized to 35 barG and storage tanks to 30 barG
Both valves have Cv = 25
Using Fathom build all of these scenarios in a single model (cryo1 (SI).fth)
What is the flow rate for all cases?
Models\Fathom Models\cryo1.fth
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Example Model (cont.)
After building all the design cases, it is discovered that pipe 1 should have been 16 inch (39.8 cm ID) schedule 5S, not 12
inch (31.6 cm ID) schedule 40S (cryo1a (SI).fth)
Make this change to the model and review the effects
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Flow rates to tanks using 12 inch (30.48 cm ID) pipe
Flow rates to tanks using 16 inch (38.9 cm ID) pipe
A B
Methane 87.2 87.5
Ethane 63.4 63.7
Propane 58.9 59.3
Flow Rate To Tank (m3/hr)
A B
Methane 87.2 87.5
Ethane 63.3 63.7
Propane 58.9 59.3
Flow Rate To Tank (m3/hr)
Answers to Example
-
Example Model (cont.)
Depending on how you arrange the scenarios, the Scenario Manager might look like this:
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View of Model Data Scenarios
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View of Output Scenarios
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AFT IMPULSE
Transient Analysis
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Overview of Transient Analysis Transient phenomenon occurs in a liquid piping system when
some event causes a departure from steady state.
Transient condition is the process the piping system experiences
as it adjusts to the new conditions.
Transient can be caused by many events including
Valve closure or opening (in full or in part)
Pump speed change
Relief valve cracking open
Tank pressurization
Periodic pressure or flow conditions
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Transient phenomenon can occur in any liquid piping system
Other terms which have been used are
Waterhammer
Fluidhammer
Hydraulic Transients
Fluid Transients
Surge
The term waterhammer confuses some, because it implies a process only in water systems
114
Overview of Transient Analysis
-
Transient can be caused by different physical mechanisms
There is no universal terminology for these mechanisms so the terminology here is for discussion purposes
1. Thermodynamic Transient Liquid acceleration caused by local phase change
2. Slug Transient Liquid flows into an evacuated pipe system or when there are
distinct liquid slugs and gas pockets
When liquid contacts equipment or direction changes (elbows) pressure spikes can occur
3. Mechanical Transient Caused by equipment or component operational changes
Pump trips, valves closed, etc.
This is the type of waterhammer that AFT Impulse can model
115
Types of Transient
-
The magnitude of a transient is dependent on the wavespeed of the liquid
The wavespeed () is dependent on the:
liquid acoustic velocity
pipe modulus of elasticity (E), wall thickness (t), and material Poisson Ratio ()
pipe restraints
A useful equation for theoretical pressure surge is given by the instantaneous waterhammer equation
116
Instantaneous Transient
=
-
Most engineers believe the instantaneous waterhammer equation defines the maximum possible pressure from
waterhammer.
This is incorrect. Several real world affects can increase the waterhammer pressure:
Pipe friction
Cavitation
Network effects (superposition of pressure waves)
117
Instantaneous Transient (cont.)
-
Code Compliance
Once the overpressure is calculated, What should the designer do with
this value?
The answer to this question depends on the code being used.
ASME Code for pressure piping B31.4. Pressure Transportation Systems for Liquid Hydrocarbons and Other Liquids.
B31.4 refers directly to the maximum value of the overpressure,
establishing a limit of 10% above the design pressure.
ASME Code for pressure piping B31.3. Process Piping
The maximum stress produce the loads created by the surge pressure
shall not exceed: 1.33 Sh (Sh=allowable stress for the operating
temperature).
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AFT Impulse
-
120
Waterhammer Sequence
a
V=Vsteady
V=0
a
b
c
d
a
V= Vsteady
V=0
a
V= Vsteady
V=0
a
V= Vsteady
V=0
-
121
Waterhammer Sequence 0 < t < L/a
P
V
Vsteady
DPinstantaneous
Valve closed instantaneously at t=0
Psteady
x
x
a
V=Vsteady
V=0
-
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Waterhammer Sequence L/a < t < 2L/a
a
V= Vsteady
V=0
P DPinstantaneous
Valve closed instantaneously at t=0
Psteady
x
V
x
-Vsteady
-
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Waterhammer Sequence 2L/a < t < 3L/a
a
V= Vsteady
V=0
Valve closed instantaneously at t=0
P
DPinstantaneous Psteady
x
V
x
-Vsteady
-
124
Waterhammer Sequence - 3L/a < t < 4L/a
a
V= Vsteady
V=0
Valve closed instantaneously at t=0
P
DPinstantaneous Psteady
V
Vsteady
x
-
Mass / continuity equation
Momentum equation
125
Fundamental Equations
2
+
= 0
1
+
+ sin +
2= 0
Where : a = wavespeed V = velocity x = distance along pipe P = pressure t = time g = gravitational constant a = slope of pipe f = friction factor D = diameter of pipe
Note: These are only the primary equations, not the complete set.
-
By combining the mass and momentum equations linearly and
substituting mass flow rate, , for velocity, V, one obtains
Integrating along the characteristic line from A to P yields the positive characteristic
126
Method of Characteristics
t = 0
t = D t
t = 2 D t
t = 3 D t
t = 4 D t
t = 5 D t
x = 0 x = L
A B
P
x = i x = i+1 x = i-1
C + C -
+
+ +
22 = 0
+
+
+
22
= 0
+
+ +
22 = 0
(Note: a similar equation can be written for the negative characteristic)
-
Introducing two convenient parameters
Impedance
Resistance
127
Method of Characteristics (cont.)
t = 0
t = D t
t = 2 D t
t = 3 D t
t = 4 D t
t = 5 D t
x = 0 x = L
A B
P
x = i x = i+1 x = i-1
C + C -
Note that after the initial calculations the impedance and resistance have constant property values for each pipe,
except for the friction factor, f
=
=
22
Where:
A = cross sectional area
-
The Transient Solver requires the following:
Initial steady-state flow rates in all pipes
Initial pressures at all junctions
Initial states of all junctions
Pumps on or off
Valve open or closed
Check valves open or closed
Etc.
Pipe resistance (friction factors)
128
Steady-State Data in Transient Solver
-
129
AFT Impulse Examples
-
Determine the surge pressures in an ammonia transfer system when a valve is closed in 0.5, 1 and 2 seconds
All pipe is steel with standard wall thickness, thin-walled anchored upstream Models\Impulse Models\Ammonia Transfer
System Valve Transient.imp
130
Model 1: Valve Closure Surge Transient
Surface Elev. = 6 m Surface Pressure = 1.72 MPa(g) Pipe Depth = 1.5 m
P1 L = 30 m 8 inch (20.3 cm ID)
Ammonia at 24C 0 to 5 seconds Model Cavitation
Surface Elev. = 12 m Surface Pressure = 1.72 MPa(g) Pipe Depth = 6 m
P3 L = 46 m 10 inch (25.5 cm ID)
Abrupt Expansion Elevation = 0 m
Valve Elevation = 0 m t (sec) Cv 0 1000 ? 0
P2 L = 91 m 10 inch (25.5 cm ID)
1 2 3 4
-
131
Model 1: Valve Closure Model
-
132
Model 1: Valve Closure Valve Input
-
Results
(*) The first two cases yield different pressures when the
sectioning is varied
This is a result of the cavitation model
The 2 second closure case does not cavitate
133
Model 1: Valve Closure - Results
Closure Max Stag. Pressure* Time (sec) (MPa(g)) 0.5 4.183 1 4.145 2 2.502
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Animation for 2 second closure case
134
Model 1: Valve Closure - Animation
-
Determine the surge pressures in gasoline product pipeline when the pumps trip
Steel pipes, standard schedule, thin-walled anchored upstream
135
Model 2: Pump Trip Surge in a Pipeline
-
136
Model 2: Pump Trip Surge - Input
-
137
Model 2: Pump Trip Surge Gasoline
Models\Impulse Models\Gasoline Pipeline Pump Trip.imp
-
138
Model 2: Pump Trip Surge Pump Data
-
The one pump junction represents 3 pumps in parallel
139
Model 2: Pump Trip Surge Pump Data
-
140
Model 2: Pump Trip Surge Pump Data
-
141
Model 2: Pump Trip Surge Maximum and Minimum Pressures
-
142
Model 2: Pump Trip Surge Animate Pressures
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Webinar Agenda
About Applied Flow Technology
Industry Applications
Overview of AFT Software
AFT impulse
Pipe Network Design Challenges
Pipe Network Design Challenges and AFT products
Overview of Transient Analysis
Types of Transient
Instantaneous Transient
Code Compliance
AFT Impulse Examples
Valve Closure Surge Transient
Pump Trip Surge in a Pipeline
Spray System Transient
Q/A session
143
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Models\Impulse Models\Spray System Transient.imp
Find how long it takes for the flow rate to come up to the full flow of 22.7 m3/hr at each spray from the closure state
Pipe data:
Steel pipe, all schedule 40, standard roughness of 0.004572 cm
Fluid is water at 21 deg. C
Inlet stagnation pressure is 1200 kPa
Spray nozzle data:
Sprays discharge to atmosphere and open in 0.1 second
Flow Area = 3.23 square cm, Discharge coefficient = 0.6
144
Model 3: Spray System Transient
Time (sec) CdA (cm2)
0 0
0.1 1.94
10 1.94
-
145
Model 3: Spray System Model Layout
4 inch
(10.2 cm ID)
L=152 meters L=152 meters 8 inch
(20.3 cm ID) 8 inch
(20.3 cm ID)
L=3 m
L=3 meters
1-1/2 inch
(4.1 cm ID)
L=3 meters
1-1/2 inch
(4.1 cm ID)
L=3 meters
1-1/2 inch
(4.1 cm ID)
L=3 meters
1-1/2 inch
(4.1 cm ID)
L=3 meters
1-1/2 inch
(4.1 cm ID)
L=3 meters
1-1/2 inch
(4.1 cm ID)
L=3 meters
1-1/2 inch
(4.1 cm ID)
L=3 meters
1-1/2 inch
(4.1 cm ID)
El=0.3 meters El=0.3 meters
El=0.3 meters
El =
3 m
ete
rs
L=0.5 m
1-1/2 inch
(4.1 cm ID)
Typical
-
146
Model 3: Spray System Model Layout
-
147
Model 3: Spray System Spray Data
-
It takes about 0.85 seconds for the final spray to reach 22.7 m3/hr
After slightly less than 1 second the flow drops below 22.7 m3/hr
148
Model 3: Spray System - Results
Nearest Supply
Farthest From Supply
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AFT ARROW
Compressible Flow
149
-
150
-
Arrow 5.0 Overview
Models compressible network pipe systems
High to low velocity gas systems High to low pressures
Implements highly advanced graphical interface very similar to Fathom
Models open and closed systems Accurately models
Real gases Heat transfer Highly compressible (sonic and near sonic) systems
Offers broad range of innovative reporting features Balances flow and energy throughout the system Offers customizable component and property databases Includes high accurate steam/water properties to ASME Modules for:
Goal Seek & Control Cost calculations
151
-
Arrow Add-On Module Overview
GSC
Automatically determines input variables that will yield specified output values
Extends Arrows control simulation capabilities to include remote sensing
CST
Supports cost databases for piping, fittings, valves, pumps and other system components
Analyzes first and life cycle cost of piping/pump systems
Integrates system hydraulic design and cost
152
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AFT Arrow Approach to Compressible
Flow
153
Solve all governing equations simultaneously Include all thermal and real gas effects Balance mass and energy throughout the network
Implement special flow and energy balance iterative methods
Offer several solution methods to increase flexibility Encapsulate powerful solution method in an easy-to-use
graphical Windows interface
-
Solution Methods
154
AFT Arrow offers six solution methods Two lumped methods Four marching methods
-
Defining Gases in the System
155
Model your system using real or ideal gases AFT Standard: 28 gases to choose from ASME Steam Tables CHEMPAK Database
-
Heat Transfer - Pipes
156
Heat transfer can be calculated using one of four models
Adiabatic Isothermal Convective heat transfer Constant heat flux
-
Database
157
AFT Arrow offers custom database for these type of data
Components Fluid Properties Pipe sizes Insulation properties Fitting and losses Output configuration
Databases: local or network
-
Typical Applications
158
Pipe and duct sizing Compressor/Fan, control valve, relief valve: sizing and
selection
Simulating system operation and component interaction Choked Flow calculations Evaluating Heat Transfer in pipes and heat exchangers Trouble shoot existing systems / cause of operational
problems
-
Arrow 5.0 Scenario Manager
159
Scenario Manager The Scenario Manager allows you to keep variants of a model all with the
same model
When changes are made to the base model, they are automatically passed downward
Changes at lower levels do not pass upwards
-
160
AFT Arrow Examples
-
Building a model
161
-
Model a Compressed Air System
162
-
Model a Compressed Air System
Models\Arrow Models\Compressed Air System.aro
Four machine tools are supplied air for operations
The air is taken from outside the building (P = 14.7 psia), and design conditions are that air temperature can vary from 0
deg. F to 110 deg. F.
The compressor has the following data for stagnation pressure: 12 psid at 0 lbm/s, 10 psid at 0.5 lbm/s, and 6 psid
at 1 lbm/s
Efficiency is not known with certainty, but is expected to be about 80% to 90% - use the Determine From Efficiency Data option for the Compression Process Thermodynamics
163
US
-
Model a Compressed Air System (2)
The nozzles at the tools (modeled as valves) have a pressure drop of 8 psid at 0.2 lbm/s
Discharge is to atmospheric pressure (make them exit valves)
Hint: Use "Fill as Quadratic" feature to create a curve
The pipes are uninsulated, sch40 steel with external heat transfer coefficients that vary from 1-10 Btu/hr-ft2-R,
exchanging heat with the internal building ambient which can
range from 70 to 75 degrees.
The pipe at the compressor inlet is heavily insulated (consider it adiabatic)
164
US
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Model a Compressed Air System (3)
The branches can be modeled as lossless
Use Redlich-Kwong and Generalized for the equation of state and enthalpy model
Neglect elevation changes
The machine tools are sensitive to temperature, but the manufacturer says they can compensate for this if they know
the extremes of delivery temperature the tools will see. What
are the (static) temperature extremes at the tools?
Hint: Compressor temperature rise increases with decreasing efficiency
Hint : Look at pipes P6-9 outlet temperatures for tool supply temperatures
165
US
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Dynamic mixing
166
Assemble non-reacting mixtures (using Chempak Database) Analyze dynamic mixtures resulting from intersecting flow streams Models\Arrow Models\Mix1.aro
-
Refinery Relief System
167
US
P1
L=50. 3 inch
schedule 40
P2
L=25. 3 inch
schedule 40
P3
L=50. 3 inch
schedule 40
P4 L=25.
4 inch schedule 40
P5
L=50. 3 inch
schedule 40
P6
Main Relief Line L=150 6 inch schedule 40
J5 Tee or Wye
J6 Tee or Wye
PIPE UNITS L= feet
J1 Methane Process
200 psia, 300F
J2
Ethane Process 200 psia, 300F
J3
Propane Process 200 psia, 300F
J7 Primary
Relief Valve
CdA=15 in2
J4 Bend
K=0.538
-
Refinery Relief System
Models\Arrow Models\Test10.aro
A new emergency relief system at an oil refinery is being considered and you have been called as a consultant to
evaluate the process calculations (model TEST10.ARO)
The system provides relief to processes for methane, propane and ethane (use Chempak to specify three fluids at the same
time)
Each process is at 200 psia when the relief event occurs
The process engineer has evaluated the relief capacity at the minimum process temperature of 300 F
The elbow is a standard elbow, and model the tees as simplified
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US
-
Refinery Relief System (2)
The relief valve CdA is 15 sq. inches (assume K = 0 since this will choke)
Discharge pressure is 1 standard atmosphere
All pipe is steel
Assume adiabatic flow
Determine the following:
Relief capacity (i.e., flow rate) of each process
Mass and mole fraction of the discharge mixture for environmental impact assessment
Hint: in Output Control, use Concentration Mass and Mole Fraction
169
US
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Model Control Valve (condensation)
Fluids in the AFT Standard database do not have saturation line data
It is not possible to evaluate condensation
Chempak fluids and the ASME Steam data do have saturation line data
Use steam data from the Chempak database to evaluate whether condensation will occur. Does it?
TEST3.ARO - "Chempak - No Insulation" Scenario
170
US