Flarenet Model Setup

Fan, Yi

Preparation before model setup

PRV Datasheets (only those relieve to flare)– Type, number and size– Set pressure and relief Condition (T, P)– Relief Load (required flow, and rated flow)

Plot Plan (if isometric drawing not available)– To identify PRV location– To measure the preliminary line length– To determine the fire zone

Relief load composition for global, fire and controlling case for each control valve

– Basis for a correct and accurate Flarenet model– Obtained from simulator (HYSYS, Pro II or ASPEN Plus)– Suggestion: Create a composition list in relief valve calculation sheet, at

least global case, fire case and controlling case.

Preparation before model setup

Utility P&ID of Flare System– Help to find P&ID for each relief valve– Get line number for header and laterals.

Flare System Piping Class– From System group and ensure correct piping schedule

used for model calculation

Relief System Design Basis– Get constraints for specific project.– Mach Number, Velocity, Noise

Flarenet Model Setup- Start a new model

Basic info Main component Select Unit Edit preference Input piping class

Flarenet Model Setup- Build the model in PFD

Flarenet Model Setup- Build the model in PFD

Data input for model component– Flare tip and KO drum– Piping– Tee and Connector– PRV

Flarenet Model Setup- Build the model in PFD

Create Scenarios– Global relief scenario– Fire Zone scenario– Depressurization scenario– Individual PRV controlling scenario

Running Flare Model

Calculation Option Header sizing

– Global Scenarios (Power failure, Cooling water failure, Instrument air failure, and Steam failure, etc.

– Depressurization– Some big individual relief (non-global)– Fire Zone

Tailpipe sizing– Use rated flow– Normally 1 or 2 nominal size above PRV outlet flange size– Main concern is MABP

Result Check

Variable check Result Message check Visual check

Some Tips

Thermodynamic deviation Choking problem during tail pipe sizing How to speed up tail pipe sizing Import data from HYSYS

Aspen Support: http://support.aspentech.com/

Question?

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