SIMULATION SUITE - chemcad.co.uk

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SIMULATION SUITECHEMCAD SOFTWARE

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CHEMSTATIONS SOFTWARE SEMINAR

PIPING NETWORKS & HEAT EXCHANGERDESIGN & RATING

Presenter John Edwards

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PIPING SYSTEM RATING & DESIGN• Review energy balance theory• Understand derivation of resistance coefficients• Develop user resistance coefficients • Understand control valve characteristics & sizing parameters• Design and rate piping distribution networks• Design and rate complex networks using Nodes

CHEMCAD REFRESHER• Review CHEMCAD plot facilities• User component for aqueous mixtures• Introduce CHEMCAD sizing features • Introduce control valve UnitOp• Excel Data mapping facility use

PIPING SYSTEM DESIGN OBJECTIVES

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FLUID FLOW THEORY - BASICS

Continuity Equation

Bernoulli’s Equation

Combining for p1= p2 and z1 = z2

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FLUID FLOW THEORY - FRICTION FACTOR

g2v

DLf

h2

L =

f4f F=

g2v

DLf4

h2

FL =

Darcy Equation Form (CHEMCAD)

Darcy > Fanning Friction Factors

Fanning Friction Factor Equation Form

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g2v

DLf4

h2

FL =

Darcy Friction Factor

Fanning Friction Factor

Fanning Friction Factor Equation Form

Laminar Flow Conditions Re < 2300

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Jain Equation Solves Darcy Friction Factor

Churchill Friction Factor Validity

Validity 10-6 < ε / D < 10-2 and 5000 < Re < 108

Applicable for all values of ε / D and Re

CHEMCAD Methods

Jain is default method

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FLUID FLOW THEORY - MOODY CHART

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FLUID FLOW THEORY - COMMON LOSSES

Loss due to Sudden Contraction

Loss at Entry to Pipe

Loss at Exit from Pipe

g2v

15.0h212

L

−= β

g2v

5.0h21

L =

g2v

h21

L =

g2v

Kg2vKh

22

2

22

41

L ==β

Final Form > Velocity v2 in Larger Diameter

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PIPING DESIGN - ORIFICE PLATE BASICS

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PIPING SYSTEM DESIGN - NETWORKS

All Flows and Pressures are dependent

Flowrates can be calculated as a function of Inlet Pressure (Pin) & Outlet Pressure (Pout)

Flow Scaling UnitOps solve for flowrate as a function of Pin and Pout

Node UnitOps link all Flow Scaling UnitOps

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PIPING SYSTEM DESIGN - FLOW SCALERS

Pipe (PIPE)Valve (VALV)Control Valve (CVAL)Pump (PUMP)Compressor (COMP)Expander (EXPN)Pin, Pout, and Flowrate for all Unit Ops

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PIPING SYSTEM DESIGN - NODES

Links two or more Flow Scaler Unit OpsSimultaneously solves unknown variablesHas P and Fin and FoutSpecify eitherP and Fin, calculate FoutP and Fout, calculate FinFout and Fin, calculate P

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PIPING SYSTEM DESIGN - NODES

Can have 1 flow in and 1 flow out Must satisfy degrees of freedomP + Fn = n + 1 variables

1 degree of freedom so must specify n variables

Example3 flows into and 2 flows out of same NodeP + Fn = n + 1, n = 56 variables with n (5) that must be specified

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PIPING SYSTEM ISOMETRIC - PUMP CURVE

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PIPE NETWORK WITH NODES

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PIPE UNITOP AS FLOW SCALER

Allows Flow to be set by UnitOp

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PUMP UNITOP AS FLOW SCALER

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INLET AND OUTLET NODES

Inlet Node

Outlet Node

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NODES BETWEEN FLOW SCALER UNITOPS

P set as either Variable or Fixed

Set the Flow as fixed or variable

Boundaries

for the pressure

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PIPING SYSTEM DESIGN PUMP NPSH

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HEAT EXCHANGER DESIGN OBJECTIVES

SHELL & TUBE HEAT EXCHANGER DESIGN• Understand temperature and phase changes across Heat Exchanger• Be able to specify a heat exchanger• Understand heat curves and pinch conditions• Be able to estimate heat transfer and fouling coefficients• Design shell and tube heat exchangers

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HEAT EXCHANGER THERMAL MODELS

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CHEMCAD HEAT EXCHANGER DESIGN

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TEMA HEAT EXCHANGER LAYOUTS

TEMA CLASS APPLICATIONR Severe requirements of petroleum and related process applicationsC Moderate requirements of commercial and general process applicationsB Chemical process service

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HEAT EXCHANGER TUBE DIMENSIONS

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HEAT EXCHANGER TUBE COUNTS

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HEAT EXCHANGER TYPICAL OHTC

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HEAT EXCHANGER FOULING RESISTANCE

SIMULATION SUITE - chemcad.co.uk

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