Aspen Plus - Bootcamp - 12 Case Studies (2 of 2) (Slideshare)

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 Rigorous Unit Operations
8. Heat-X Rigorous Model (Shell & Tube)
9. RadFrac for Absorption Operations
10. RadFrac in Distillation Operations

 Heat Streams
 Rigurous Methods
 Shell & Tube Exchanger
 Plate Exchanger
 Rating vs. Design
 Design vs. Simulation

 Benzene stream is to be heated from 75°F to 145°F @50psia
 O-toluidine is to be used as heating material. It is available at 230°F and should not drop
below 150°F @45 psia
 Max. Pressure dorp is 10 psia per side (Tube/Shell)
 Identify the best Heat Exchanger if this must be a small heater, i.e. use multiple passes (6)
to avoid long sizing
www.ChemicalEngineeringGuy.com https://www.youtube.com/watch?v=wE8TxtWKX18
https://www.youtube.com/watch?v=9-UdleyXfUs

 (A) Verify Energy Balances  Heating and Cooling Duties
 Get Mass require of heating fluid
 Get Heat duty of heat exchanger
 (B) Get Heat-X  Shortcut
 (C) Convert to Rigorous, verify results
 (D) Specify Shell & Tube Exchanger
 (E) Change conditions
 HEAT-X  RATING!
 If Benzene Inlet  90,000 lb/h to 100,000 lb/h to 120,000 lb/h to 180,000 lb/h

 Try to get something similar to this:

 Physical Property Environment

 (A) Verify Energy Balances  Heating and Cooling Duties

 Simulation 1
 Verify Energy Balances  Heating and Cooling Duties
 Guess Mass  100,000 lb/h

 Get Design Spec
 Vary to get Mass Flow… T = 150F o-tol out

 Results…
 Mass Flow = 68642 lb/h

 Add Heat flow
 No need to specify Heat duties in UNITS
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 Select TEMP
 Avoid DUTIES

 Select TEMP
 Avoid DUTIES
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 Results

 (C) Convert to Rigorous

 Size with recommended data
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 Size with recommended data

 Accept Design, Verify Results

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 From EDR Results only:
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 HEAT-X  RATING!
 If Benzene Inlet 
 90,000 lb/h to 100,000 lb/h

 If Benzene Inlet 
 90,000 lb/h to 120,000 lb/h

 Learn to stablish relevant column internals in RadFrac
 Pressure Profile
 Temperature Profile
 Molar Flow Rate Profile
 Selecting between trays and packings

 Acetone is to be absorbed into water from air mixture
 Specs: 15 Stages, P = 1 atm, Isobaric
 Feed Gas:
 %Acetone = 2%; Air = 98%
 F = 80 kmol/h, T = 25°C, P = 1 atm (101.3 kPa)
 Solvent
 %Water = 100%
 F = 80 kmol/h, T = 25°C, P = 1 atm (101.3 kPa)

 (A) Perform the Simulation of Absorption, verify Results
 (B) Compare Sieve Trays vs. Bubble-Cap Trays
 (C) Change Tray Spacing to verify results
 (D) Change from Tray Columns to Packed Column, verify Results

 Try to get:
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 (A) Perform the Simulation of Absorption, verify Results

 Acetone:
 2% initially
 0.3% finally

 (B) Compare Sieve Trays vs. Bubble-Cap Trays
 Now, continue to calculate the height and diameters:
 Assume:
 Trays
 Sieves
 Packed column:
 Rashing Rings
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 for:
 Trays  Sieve
 Spacing = 0.6096 m recommended  0.5436m diameter

 RUN an get:
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 for:
 Trays  Bubble-Caps
 Spacing = NA m recommended  0.855 diameter

 From 0.5m to 0.80 m
 Verify Pressure drop, Column Diameter and

 From 0.5m to 0.20 m
 Verify Pressure drop, Column Diameter and
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 If required, you could change the % flood approach
 Typical values are between 70-80%

 From trays  Packing
 Select RASHIG Rings
 Metallic 25-mm

 Select BETA-Rings
 Metallic No. 2
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 Select BETA-Rings
 Metallic No. 2

 Use RadFrac for rigurous distillation operations
 Multiple / Binary Distillation
 D:F, RR, DR effects
 Number of Stages
 Use Sensitivity Analysis
https://www.youtube.com/watch?v=8P3vOOXbiF4
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 A 1:2 water-methanol mixture must be separated
 The feed conditions are given as follows:
 P = 18.4 psi, T = ? Unkown, X = saturated vapor, i.e. it is in its dew point
 Water = 0.632 and Methanol = 0.368; asume mol Flow raltes
 Since polar-polar interaction, use activity models such as NRTL / NRTL-RK
 A series of analysis are to be run
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 (A) Run a RadFrac for this Distillation Column, optimize No. Stages, Feed, Recycle
Ratio and purities.
 (B) Change Column Internals
 (C) Perform Sensitivty Analysis on the column
 S-1 : Vary Feed Stage (1-9); verify Purity of Distillate
 S-2 : Vary Reflux Ratio (1.5-5); verify Purity of distillate
 S-3 : Vary Operating Pressure (Stage 1 – Condenser P = (18.4-184); verify Purity of distillate
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 Try to get this:
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 Simulation Env.
 FEED:
Column Spec:
Feed  5
dP = 0
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 Phys.Prop.Env.
 Components  water, metanol
 Prop. Method  NRTL-RK
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 FEED
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 Simulation Environment
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 Add 
 Trays
 Packaging
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 (B) Compare Tray Column vs. Packed Column
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 Trays input/results
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 Packing input/results
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 (C) Apply Sensitivity Analysis for further Analysis
 Graph each result

 Defined variable is the same for all (Purity of Distillate)

ERROR  Stage 1 is the condenser (can’t feed there)

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 Plant Economy & Dynamic Control
11. Ammonia Economics
12. Plant Dynamics & Control

 Setting up Utilities
 Operating Costs Reports
 Setting up Material Cost
 Raw Material pricing
 Optimization of profits
 What if scenarios
www.ChemicalEngineeringGuy.com https://www.youtube.com/watch?v=bWJ2A28oPW0&t=18s

 Ammonia is to be produced via the reaction of N2 and H2 using the Haber process.
There is no oxygen in the feed, only trace material such as methane, argon and
carbon monoxide. The reactor is isothermal, and has a 40% conversion based on the
inlet of nitrogen gas. The cryogenic mix is then cooled down to separate it. The gases,
mostly Nitrogen and Hydrogen gas are recycled, all other material purged and the
liquid product goes to the “Ammonia” product line.
 Pressure is approx. 270 atm through all the system
 Main focus is to produce 95%+ Ammonia product
 Utilities are to be added, as well as some raw materials / products economics
 Analysis is carried out in Europe and USA

 Prices in USA
 Materials
 Syngas = $0.26/kg
 Product = $0.50/kg
 Utilities
 Electricity = $0.06/kWh
 Cooling Water = $0.0251$/tonne  -33.44 kJ/kk
 Natural Gas = $5.8 / MMBTU  $20.63 MBTU/lb
 Prices in EU
 Materials
 Utilities
 Cooling Water = $0.0301$/tonne  35.44 kJ/kk

 (A) Create the plant
 (B) Add Materials Costs & Utilities
 (C) Compare USA vs. Europe Costings
 (D) Sensitivity Analysis of Prices
 (E) Verify the “Economic Analysis” and Economic Reports

 The flowsheet should look something similar to this:

 (A) Create the plant
 Physical Property Environment.

 Simulation Environment
 FEED

 Unit Operations

 Unit Operations - RKT
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 Add Recycle Stream

 (B) Add Cost & Prices
 Prices in USA
 Materials
 Utilities
 Cooling Water = $0.0251$/tonne  60 kJ/kg (20°C-35°)
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 Prices in USA
 Materials
 Utilities

 Prices in USA
 Materials
 Utilities
Q = m*c*dT
Q=(1kg)(4.18kJ/KgC)(35-25°
Q= 62.4 kJ/kg
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 Prices in USA
 Materials
 Utilities
 Natural Gas = $3.50 / MMBTU

 Prices in USA
 Materials
 Utilities

 Prices in EUROPE
 Materials
 Utilities

 Add Utilities to each unit
 Compressors  electricity
 Heaters  Gas
 Coolers  Water
 Isothermal Reactors  Water for Exothermic, Gas for Endothermic

 RESULTS
 $, k$, or MM (million $)
 S, h, Day, Year

 RESULTS
 $, k$, or MM (million $)
 S, h, Day, Year
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www.ChemicalEngineeringGuy.com https://www.youtube.com/watch?v=ZPCGXMPtM_U
 Aspen Dynamics Software
 Setting up Dynamic Folders
 Exporting to Dynamics
 Dynamic & Control
 Flow driven simulation
 Pressure driven simulation
 Adding Controllers
 Tuning Controllers

 A distillation column of Benzene-Toluene mix (50-50% molar) is to be separated
 The Pressure of the column is 1 bar, and has a 0.2 psi pressure dropper stage
 Condition of the feed  500 mol/h, 25°C, 5bar
 Valve 1 will adjust pressure to the 20th stage pressure, approx. P = 1.262bar
 D = 250 mol/h approx., 99% purity required
 Ppressure  +6 bar extra
 Pvalve  pressure drop 3 bar

 The idea is to:
 Create Aspen Plus – Simulation
 Add the Dynamic Data Requirements
 Export to Dynamics
 (a) Verify the pressure Controller
 (b) Add Flow-Controller to the feed
 (c) Add Level-Controllers to the vessels in reflux/reboiler streams
 (d) Add and tune a Temperature-Controller in the 34th stage - Reboiler

 Try getting something similar to this:

 Pvalve = P-stage 20,

 Results

 Recommended control stages:
 N = 34

 Sizing:
 RADFRAC 
 Diameter
 D = 2.399 m (given)
 Total height
 h = 1.2(0.61)(N-2) = (120%)(0.6096m)(40-2 trays) = 27.8 m
 Reflux Tank (Receiver)
 5 min retention time
 Assume cylindrical
 Q =0.9011 m3/min
 D = 1.8m, L = 3.6m

 Go dynamics…
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 Controllers

RUN Simulation
EXPORT  Pressure Driven

 Add Step Function
 1) Normal run:
 Step  up + 1%
 Verify time of stabilization
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 Add Step Function
 1) Normal run:
 Step  up + 1%
 Verify time of stabilization

 Now change tuning
 From previous test:

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 Add a Flow Controller
 Get info FROM:
 Pre-Feed Stream
 Send info TO
 B1 (Flow controller)
 STREAM(‘PRE-EED’)F , Total mole flow

 Add a Flow Controller
 Get info FROM:
 Flow-Controller
 Send TO
 V1 (valve1)

 Add a Level Controller (BOTTOMS)
 Get info FROM:
 Level-Controller
 Send TO
 V3 (valve3)
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 Add a Level Controller (Distillate)
 Get info FROM:
 Flow-Controller
 Send TO
 V2 (valve2)

 Flow-Controller
If flow increases, valve must close to avoid
accumulation in tower
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 Flow-Controller
If flow increases, valve must open to avoid
accumulation in tower

 Add Temperature

 Add Temperature
 Steup tuning
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 Add Temperature
 Steup tuning

 Finally! You made it!
 By now you should be able to know:
 General Flowsheet Concepts
 Basic Requirements to set up a Simulation
 Setting the adequate Physical Properties
 Flowsheet “manipulation”
 Major and Common Unit Operations
 Workshop Practice
 Reporting Results (Tables)
 Technical Stuff (extensions, versions, exporting, saving, etc...)

Aspen Plus - Bootcamp - 12 Case Studies (2 of 2) (Slideshare)

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Aspen Plus - Bootcamp - 12 Case Studies (2 of 2) (Slideshare)