Process Design Eco Ppt

Prof. Adnan AlamerChemical Engineering Dept., KFUPM.

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CHE 425 CHE 425

Engineering Economics and Engineering Economics and Design PrinciplesDesign Principles


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CHAPTER 1 CHAPTER 1 Chemical Process DiagramsChemical Process Diagrams

THE MOST EFFECTIVE WAY OF THE MOST EFFECTIVE WAY OF COMMUNICATING INFORMATION COMMUNICATING INFORMATION

ABOUT A PROCESS IS THROUGH ABOUT A PROCESS IS THROUGH THE USE OF THE USE OF FLOW DIAGRAMSFLOW DIAGRAMS


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The Generic Block Flow Process Diagram

There are features common to all chemical processes. Figure below provides a generic Block Flow Process Diagram that shows a chemical process broken down into six basic areas or blocks.


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The Generic Block Flow Process DiagramEach of these blocks may contain several unit operations. For example, A separation section might contain (four distillation columns, two flash units, and a liquid-liquid decanter)

Reactor Feed preparation and Separator Feed Preparation sections mainly involve changing the conditions (temperature and pressure) of the process streams to the conditions required by the reactor or separator.


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CHAPTER 1 CHAPTER 1 Chemical Process DiagramsChemical Process Diagrams

Design is an evolutionary process:

Input/output is a crude block flow diagram in which only feed and product streams are identified.

Generic Diagram Break the process into its basic elements such as reaction and separation , and recycle sections.

BFD include the material balance calculations.

PFD complete mass and energy balance and preliminary equipment specs.

P&ID includes the mechanical and instrumentation details.

Input/output diagram Generic diagram BFD PFD P&ID.


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Chemical Process DiagramsChemical Process Diagrams

3 Main Levels of Diagrams

Block Flow Diagram (BFD)

Process Flow Diagram (PFD)

Piping and Instrumentation Diagram (P&ID) – often referred to as Mechanical Flow Diagram


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Comparison Comparison

BFDBFD

PFDPFD

P&IDP&ID

Level of ComplexityIncreases

Level of Conceptual

UnderstandingIncreases


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The Block Flow Diagram (BFD) The Block Flow Diagram (BFD)

Shows overall processing picture of a Shows overall processing picture of a chemical complex chemical complex

Useful as an orientation tool Useful as an orientation tool

Used to sketch out and screen potential Used to sketch out and screen potential process alternatives.process alternatives.


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Definitions of BFD Definitions of BFD

Block Flow Process Diagram (BFPD)Block Flow Process Diagram (BFPD)BFPD forms the starting point for developing BFPD forms the starting point for developing PFD PFD BFPD is helpful in conceptualizing new BFPD is helpful in conceptualizing new processesprocessesSee Fig 1.1See Fig 1.1

Block Flow Plant Diagram Block Flow Plant Diagram Gives a general view of a large complex plantGives a general view of a large complex plantSee Fig 1.2See Fig 1.2


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The Block Flow Process Diagram The Block Flow Process Diagram


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The Block Flow Plant Diagram The Block Flow Plant Diagram


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Block Flow DiagramsBlock Flow Diagrams

Conventions and Formats Conventions and Formats for BFD

Operations shown by blocks

Major flow lines shown with arrows

Flow goes from left to right whenever possible

Light streams toward top with heavy stream toward bottom

Critical information unique to process supplied

If lines cross, then horizontal line is continuous

Simplified material balance provided


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The Process Flow Diagrams (PFD)The Process Flow Diagrams (PFD)

A PFD contains the bulk of the A PFD contains the bulk of the ChemChem Eng data Eng data necessary for the design of a chemical process.necessary for the design of a chemical process.

Basic information provided by a PFD:Basic information provided by a PFD:

Process TopologyProcess Topology

Stream InformationStream Information

Equipment InformationEquipment Information


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The Process Flow Diagrams (PFD)The Process Flow Diagrams (PFD)

A typical commercial PFD will contain the A typical commercial PFD will contain the following information:following information:

All major pieces of equipments in the process will be All major pieces of equipments in the process will be represented along with a descriptive name and represented along with a descriptive name and number.number.All process flow streams will be shown and identified All process flow streams will be shown and identified with a number. A description of the process conditions with a number. A description of the process conditions and chemical composition of each stream will be and chemical composition of each stream will be included.included.All utility streams supplied to major equipment that All utility streams supplied to major equipment that provides a process function will be shown.provides a process function will be shown.Basic control loops will be shown.Basic control loops will be shown.


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The Process Flow Diagram (contThe Process Flow Diagram (cont’’d) d)

The topology of the process The topology of the process –– showing the showing the connectivity of all the streams and the connectivity of all the streams and the equipmentequipment

Example for toluene HDA Example for toluene HDA –– figures 1.3 and 1.5 figures 1.3 and 1.5

Tables 1.2 lists information that should be on the PFD Tables 1.2 lists information that should be on the PFD but cannot fit but cannot fit

Use appropriate conventions Use appropriate conventions –– consistency is important consistency is important in communication of process information in communication of process information ex. Table 1.2ex. Table 1.2


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Symbols for Drawing PFDSymbols for Drawing PFD


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Table 1.2 : Conventions Used for Identifying Process Equipment

Process Equipment General Format XX-YZZ A/BXX are the identification letters for the equipment classificationC - Compressor or TurbineE - Heat ExchangerH - Fired HeaterP - PumpR - ReactorT - TowerTK - Storage TankV - VesselY designates an area within the plant ZZ are the number designation for each item in an equipment classA/B identifies parallel units or backup units not shown on a PFD

Supplemental Information

Additional description of equipment given on top of PFD


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Equipment NumberingEquipment Numbering

XXXX--YZZ A/B/YZZ A/B/……

XX represents a 1XX represents a 1-- or 2or 2--letter designation for the letter designation for the equipment (P = pump) equipment (P = pump)

Y is the 1 or 2 digit unit number (1Y is the 1 or 2 digit unit number (1--99) 99)

ZZ designates the equipment number for the unit (1ZZ designates the equipment number for the unit (1--99)99)

A/B/A/B/…… represents the presence of spare equipmentrepresents the presence of spare equipment


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Equipment Numbering (contEquipment Numbering (cont’’d)d)

Thus, TThus, T--905 is the 5th tower in unit nine hundred P905 is the 5th tower in unit nine hundred P--301 301 A/B is the 1st Pump in unit three hundred plus a spareA/B is the 1st Pump in unit three hundred plus a spare XXXX--YZZ A/B/YZZ A/B/……

Use unambiguous letters for new equipment Use unambiguous letters for new equipment

Example: Turbine use Tb or J not T (for tower) Example: Turbine use Tb or J not T (for tower)

Replace old vessel VReplace old vessel V--302 with a new one of different design 302 with a new one of different design --use Vuse V--319 (say) not V319 (say) not V--302 302 –– since it may be confused with since it may be confused with original Voriginal V--302302 the presence of spare equipmentthe presence of spare equipment


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Stream Numbering and Drawing Stream Numbering and Drawing

Number streams from left to right as much as possible

Horizontal lines are dominant


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Stream Numbering and Drawing (contStream Numbering and Drawing (cont’’d) d)

Add arrows for Add arrows for

Change in direction Change in direction

Inlet of equipment Inlet of equipment

Utility streams should use convention given in Table Utility streams should use convention given in Table 1.3 (1.3 (lpslps, , cwcw, , fgfg, etc), etc)


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Stream Information Stream Information

Since diagrams are small not much stream Since diagrams are small not much stream information can be included information can be included

Include important data Include important data –– around reactors and towers, around reactors and towers, etc. etc.

Flags are used Flags are used –– see toluene HDA diagram see toluene HDA diagram

Full stream data, as indicated in Table 1.4, are included in a Full stream data, as indicated in Table 1.4, are included in a separate flow summary table separate flow summary table –– see Table 1.5see Table 1.5


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Stream Information Stream Information -- FlagsFlags


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Stream Information Stream Information

Essential InformationEssential InformationStream NumberTemperature (°C)Pressure (bar)Vapor FractionTotal Mass Flow Rate (kg/h)Total Mole Flow Rate (kmol/h)Individual Component Flow Rates (kmol/h)

Optional InformationComponent Mole FractionsComponent Mass FractionsIndividual Component Flow Rates (kg/h)Volumetric Flow Rates (m3/h)Significant Physical Properties

DensityViscosityOther

Thermodynamic DataHeat CapacityStream EnthalpyK-values

Stream Name

Table 1.4: Information in a Flow Summary


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A Portion of Table 1.5Stream Number 1 2 3 4 5 6 7 8 9 10

Temperature (°C) 25 59 25 225 41 600 41 38 654 90

Pressure (bar) 1.90 25.8 25.5 25.2 25.5 25.0 25.5 23.9 24.0 2.6

Vapor Fraction 0.0 0.0 1.00 1.0 1.0 1.0 1.0 1.0 1.0 0.0

Mass Flow (tonne/h) 10.0 13.3 0.82 20.5 6.41 20.5 0.36 9.2 20.9 11.6

Mole Flow (kmol/h)108.7

144.2 301.0 1204.4 758.8

1204.4

42.6 1100.8

1247.0

142.2

Component Mole Flow (kmol/h)

Hydrogen 0.0 0.0 286.0735.4 449.4 735.4

25.2651.9 652.6

0.02

Methane 0.0 0.0 15.0317.3 302.2 317.3

16.95438.3 442.3

0.88

Benzene 0.0 1.0 0.0 7.6 6.6 7.6 0.379.55 116.0

106.3

Toluene108.7

143.2 0.0144.0

0.7144.0

0.041.05

36.0 35.0


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Equipment Information Equipment Information

Equipment are identified by number and a label (name) positioned above the equipment on the PFD

Basic data such as size and key data are included in a separate table (Equipment Summary Table) Table 1.7 (and Table 1.6) in TBWS


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Equipment Information Equipment Information

A Section of Table 1.7: Equipment Summary

VesselVessel VV--101101 VV--102102

Temperature (Temperature (ººC)C) 5555 3838

Pressure (bar)Pressure (bar) 2.02.0 2424

OrientationOrientation HorizontalHorizontal VerticalVertical

MOCMOC CSCS CSCS

SizeSize

Height/Length (m)Height/Length (m) 5.95.9 3.53.5

Diameter (m)Diameter (m) 1.91.9 1.11.1

InternalsInternals s.ps.p. (splash plate). (splash plate)


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PFD Summary PFD Summary

PFD, Equipment Summary Table, and Flow Summary Table represent a “true” PFD

This information is sufficient for a preliminary estimation of capital investment (Chapter 5) and cost of manufacture (Chapter 6) to be made


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The Piping and Instrument Diagram (P&ID) The Piping and Instrument Diagram (P&ID)

P&ID – Construction Manual Contains: plant construction information (piping, process, instrumentation, and other diagrams)

P&ID construction convection is explained in Table1.9

Conventions for instrumentation are shown in Table 1.10.


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P&ID


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Look at VLook at V--102 on P&ID 102 on P&ID

V-102 contains an LE (Level Element)

LE senses liquid level in separator and adjusts flow rate leaving

LE opens and closes a valve depending on liquid level

LE and valve represent a feedback control loop

The final control element in nearly all chemical process control loops is a valve


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P&ID P&ID

Based on the P&ID diagram:

Mech and Civil Engrs will design and install pieces of equipment.

Instrument Engrs will specify, install and check control systems.

Piping Engrs will develop plant layout and elevation drawings.

Project Engrs will develop plant and construction schedules.


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Additional Diagrams Additional Diagrams

UTILITY FLOWSHEETVESSEL SKETCHESWIRING DIAGRAMSSITE PLANSPLOT PLANSELEVATION DIAGRAMS

DO NOT POSSESS ADDITIONAL PROCESS DO NOT POSSESS ADDITIONAL PROCESS INORMATIONINORMATION


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Plot Plans – plan or map drawn looking down on plant (drawn to scale with all major equipment identified)

Elevation Diagrams – show view from side and give information about equipments distance from ground


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Section of Plot Plan Section of Elevation Diagram


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Additional Diagrams (contAdditional Diagrams (cont’’d)d)

Piping Isometrics – show piping in 3-dimensions

Vessel Sketches – show key dimensions of equipment and locations of inlet and outlet nozzles etc.


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Scale Models and Virtual Plants Scale Models and Virtual Plants

25 years ago physical models were used for 25 years ago physical models were used for review review

Now virtual or electronic models are generated Now virtual or electronic models are generated using software (3using software (3--d plant diagrams) d plant diagrams)

Purpose of Models Purpose of Models –– catch errors such as catch errors such as Piping clashes Piping clashes Misaligned piping Misaligned piping Equipment not easily accessed Equipment not easily accessed Sample points not easily reached by operatorsSample points not easily reached by operators


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33--D Plant DiagramsD Plant Diagrams


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Problem 1.9

Figure below is a portion of a PI&D. Find at least six errors in it. All errors are actually shown on the drawing.


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Solution:Errors include:

1. LI on pump discharge should be PI.2. Direction of arrowheads should be reversed.3. TCV on control valve should be labeled FCV.4. LAH on control loop should be FAH (Since no level

signal is shown)5. Add isolation valve to the left of the control valve.6. Add a bleed valve between control valve and isolation

valve.7. Suction piping should be larger than discharge piping,

switch 4” with 8”.8. Label insulation.9. Pumps should be labeled P-102 A and P-102B.


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contd.SolutionCorrected Diagram is:


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Course Outcomes Course Outcomes

Upon successful completion of this course, the student will be able to:

Understand the process flow diagrams of a chemical process.

Understand and justify the process conditions

Be able to use heuristics in process design and analysis


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Course Outcomes (cont.) Course Outcomes (cont.)

Estimate capital investment.

Estimate manufacturing cost.

Understand engineering economics and perform profitability analysis.

Be familiar with using simulation for equipment design.

Process Design Eco Ppt

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