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2 FLOWSHEETS

Coal100,000

Air

Net Fuel G a s 71 83

Fractionator

22,500 Light Aromatics 770

Middle Oils (diesel, etc.) 12575

Sulfur 1070ulfurRecovery

I Tar Acids 3320

2380Pitch Heavy Oils (creosote, etc.)

Phenols 25I

Net Waste Liquids 2380Carbonizer Primary

Distillation

Figure 2 1 Coal carbonization block flowsheet. Quantities a re in Ib/hr

compressed air, fuel, refrigerants, and inert blanketing gases, andhow they are piped up to the process equipment. Connections forutility streams are shown on the mechanical flowsheet, and theirconditions and flow quantities usually appear on the processflowsheet.

Since every detail of a plant design must be recordedon paper,many other kinds of drawings also are required: for example,electrical flow, piping isometrics, instrument lines, plans andelevations, and individual equipm ent drawings in all detail. M odelsand three-dimensional representations by computers also are nowstanda rd practice in many design offices.

2.5. DRAWING OF FLOWSHEETS

Flowsheets are intended to represent and explain processes. Tomake them easy to understand, they are constructed with aconsistent set of symbols for equipment, piping, and operatingconditions. At present there isno generally accepted industrywidebody of drafting standards, although every large engineering officedoes have its internal standard s. Some information app ears inANSI

and British Standards publications, particularlyof piping symbols.Much of this information is provided in the book by Austin(1979)along with symbols gleaned from the literature and someengineering firms. Useful compilations appear in some books onprocess design, for instance, those of Sinnott(1983) and Ulrich(1984). The many flowsheets that appear in periodicals such asChemical Engineering or Hydrocarbon Processing employ fairlyconsistent sets of symbols that may be worth imitating.

Equipment symbols are a compromise between a schematicrepresentation of the equipment and simplicity andease of drawing.A selection for the more common-kindsof equipment appears inTable 2.2. Less common equipment or any with especially intricateconfiguration often is represented simply by a circle or rectangle.

Since a symbol does not usually speak entirely for itself but carries a name and a letter-num ber identification, the flowsheet be made clear even with the roughestof equipment symbols. T

TABLE 2.1. Checklist of Data Normally Included on aProcess Flowsheet

1.

2

3

4.56

7.

8

9.

Process lines, but including on ly those bypasses essential to anunderstanding of the processAllprocess equipment. Spares are indica ted by letter symbols ornotesMajor instrumen tation essential to process control and tounderstanding of the flowsheetValves essential to an understanding of the flowsheetDesign basis, including stream factorTemperatures, pressures, fl ow quantitiesWeight and/or mol balance, showing compositions, amounts, andother properties of the principal streamsUtilities requirements summaryData included or particular equipmenta. Compressors: SCFM (60F. 14.7 psia); APpsi;

HHP;number of

stages; details of stages if importantb. Drives: type; connected HP; utili ties such as kW, Ib steam/hr, or

Btufhrc. Drums and tanks: ID or OD, seam to seam length, important

internalsd. Exchangers: Sqft, kBtu/hr, temperatures, and flow quan tities in

and out; shell side and tube side indicatede. Furnaces: kBtu/hr, temperatures in and out, fuelf. Pumps: GPM (60F). APpsi, HHP, type, driveg. Towers: Number and type of plates or height and type of packing;

ident ifica tion of all plates at which streams enter or leave; ID orOD; seam to seam length; skirt height

h. Other equipment: Sufficient data for identification of duty and size

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2.5. DRAWING OF FLOWSHEETS 2

TABLE 2.2. Flows heet Equipment Symbols

Fluid Handlin g Heat Transfer

FLUID HANDLING HEAT TRANSFER

Centrifugal pump or blower,motor driven She l l - and- tube

heat exchanger Shellside

Process-@+entrifugal pump or blower,turbine driven CondenserReboiler

Processotary pump or blower

-8-eciprocating pump orcompressorCentrifugal compressor

Vertical thermosiphonrebo i l e r

Process

+ettle reboilerCentrifugal compressor,alternate symbol Air cooler withfinned tubesProcess-4 Process3uelSteam ejector Fired heater

Fired heater with radiantand convective coils

Coil in tank

ProcessRotary dryeror ki lnEvaporator

Tray dryer

yWaterCooling tower,forced draft

waterIII

IIIIIII

Spray condenser withsteam ejector

v

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2.5. DRAWING OF FLOWSHEETS 23

TABLE 2.2- cont inued)

Convevors and Feeders Separators

coMlEYORS& FEEDERS SEPARATORS

Jiate-and-frame filteronveyor

Belt conveyor3otary vacuum filter

Screw conveyor

Elevator

Sand filter

Dust collector

eederCyclone separator

tar feederCentrifuge

Screw feeder

4

\+G=)Mesh entrainmentseparator

Weighing feeder

Tank car T+eavy LightLiquid-l iquidseparatorFreight car

Drum with watersettling pot

Conical settlingtank

I

II

Screen Course

Raked thickener *Fine

thoroughly standardized by the Instrument Society of America For clarity and for esthetic reasons, equipment should be(ISA). An abbreviated set that may be adequate for the usual represented with some indication of their relative sizes. True scale isflowsketch appears on Figure 3.4. The P I diagram of Figure 2.6 not feasible because, for example, a flowsheet may need to depictaffords many examples. both a tower 150 ft high and a drum 2 ft in diameter. Logarithmic

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2.5. DRAWING OF FLOWSHEETS 25

TABLE 2.3. Flowsheet Flags of Operating Conditions nTypical Units

_ _ _ _ _

Mass flow rate, Ibs/hr

Mo lal flow rate, Ibmo ls/hr

Temperature,O F

Pressure, psig (or indicate if psia orTorr or bar)

Volumetric liquid flow rate, gal/min.

Volumetric liquid flow rate, bbls/day

Kilo Btu/hr, at heat transfer equipmeni

Enthalpy, Btu/lb

Others

217)

@ psia

r >

TABLE 2.4. Letter Designations of Equipment

Equipment Letters Equipment Letters

AgitatorAir filterBinBlenderBlowerCentrifugeClassifying equipmen tColloid millCompressorCondenserConveyorCooling towerCrusherCrystallizerCyclone separator (gas)Cyclone separator

(liquid)DecanterDisperserDrumDryer (thermal)Dust collectorElevatorElectrostatic separatorEngineEvaporatorFanFeederFilter (liquid )Furnace

MFGl r

MJBFFS

SRJC

EC

TESR

KFG

FFLMD

DEFG

CFGPMFEJJCPB

GrinderHeat exchangerHomogenizerKettleKiln (rotary)Materials ha ndling

equipmentMiscellaneousMixerMotorOvenPackaging m achineryPrecipitator (dust or mist)Prime moverPulverizerPump (liquid)ReboilerReactorRefrigeration systemRotameterScreenSeparator (entrainment)ShakerSpray diskSpray nozzleTankThickenerTowerVacuum equipment

SRE

MR

DDG

LM

PM

LFGPMSR

JERG

RMS

FGM

SRSRl r

FT

VEWeiah scale L~-~ -

'Note: The letter L is used for unclassified equipme nt when on ly afew items are of this type; otherwise, individual letter designations areassigned.

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I

I

1

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9

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I

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REFERENCES 31

REFERENCES

1 D.G. Austin Chemical Engineering Drawing Symbolr George GodwinLondon 1979.

2. Graphical Symbols for Piping System and Plant British Standard 1553:Part 1: 1977.

3. Graphical Symbols for Process Flow Diagrams ASA Y32.11.1961American Society of Mechanical Engineers New York.

4. E.E. Ludwig Applied Process Design for Chemical and Petrochemical

Plants Gulf, Houston 1977 Vol. 1.

Wiley New York 1957.

Design Pergamon New York 1983.

Economics Wiley, New York 1984.

5. H.F. Rase and M.H. Barrow Project Engineering of Process Plants

6 . R.K. Sinnott Coulson and Richardson Chemical Engineering vol. 6

7 G.D. Ulrich A Guide to Chemical Engineering Process Design and

8. R. Weaver Process Piping Design Gulf Houston 1973 2 vols.