Evaluating and Rating Flare Networks

Course Id:  EHY251   |   Duration:  2.00 day(s)   |   CEUs Awarded:  1.4   |   Level:  Intermediate

Course Objective

In a plant emergency, process material must safely relieve through the flare system for disposal. An important step in process design and plant revamp is to ensure that the flare network can handle the flowrates and meet design constraints on backpressure, Mach number, noise, and pipe fatigue. Aspen Flare System Analyzer has the capability to solve complex network hydraulics and incorporate industry standards. Simultaneously execute multiple emergency scenarios, identify potential process bottlenecks, and validate the capacity of the flare network. This technology can help reduce capital cost by determining optimum equipment sizes, and, more importantly, assure the safety of the plant. 

Course Overview

  • Learn the fundamental flare network modeling techniques for pipeline design.
  • Learn the basics for rating a flare convergent, divergent and looped network for the constraint violations (Mach number, MABP, Noise, velocity, RhoV2) & for pressure, temperature and flow profile throughout the network.
  • Understand the solver messages to analyze the flow network problems and review options to take corrective measures.
  • Review results to perform process safety studies for pressure & temperature beyond allowable range and erosion problems (RhoV2) for healthiness of the flow network in the real plant.
  • Review flare network simulation computation convergence problems and examine solver solution methods.
  • Discuss customize reports using MS excel macro
  • Import  sources from Aspen HYSYS®, Export and import data from the MS access and MS excel


  • Assist in process safety management and regulatory compliancy
  • Design or rate the flare system for plant contingencies
  • Develop core competencies at an accelerated pace 
  • Automate engineering workflows with Aspen Flare System Analyzer to save valuable project time
  • Discover best practices to realize the full capabilities of Aspen Flare System Analyzer
  • Earn Continuing Education Units toward P.E. licensing requirements


  • Engineers developing or validating plant Flare system models
  • Engineers debottlenecking existing plant Flare systems
  • Engineers performing relief valve calculations and studies
  • Engineers needing tips on troubleshooting and best practices
  • Engineers wanting to understand concepts and criteria of flare system modeling


  • Students receive guided instruction on all course topics 
  • Instructors provide live demonstrations of Aspen Flare System Analyzer features
  • Students participate in hands-on workshops and apply concepts presented in class 
  • Detailed course notes and workshop solutions are provided to students
  • Students retain copies of workshop files and course textbooks
  • Student-instructor Q&A


  • A background in process engineering

Subsequent Courses

Develop additional expertise with these recommended courses:

  • EHY223      Aspen HYSYS Dynamics: Introduction to Dynamics Modeling
  • EHY250      Determine Rapid Depressurization Safety Limits for Design and Rating
  • EHY252      Pressure Relief Analysis Using Aspen HYSYS

Class Schedule

Class Agenda

EHY251: Evaluating and Rating Flare Networks

Introduction to Aspen Flare System Analyzer

  • Provide brief history and overview of Aspen Flare System Analyzer
  • Review the Aspen Flare System Analyzer capabilities
  • Identify typical uses and benefits of the program
  • Review the requirements for building a Aspen Flare System Analyzer model
  • Identify common result reporting and output options
  • Workshop: Designing a Flare System - Sizing and building the pipe network.

Perform Rigorous Rating and Redesign
  • Identify and explain rigorous rating calculations
  • Improve the accuracy of the calculations by including options for more detailed calculation
  • Review Debottlenecking - identify and remove pipe constraints
  • Add flare tip curves and introduce heat transfer calculations
  • Add Flare Tip Curves and Invoke Heat Transfer calculation
  • Workshop: Rigorous Rating and Redesign - Implementing a rating check and improving the accuracy of the calculations.

Study PSV Sizing Options and Inlet Pipe Pressure Drop
  • Calculate the rated flow for the PSV using API’s methods
  • Setup the Orifice Size for PSVs
  • Calculate the Critical Pressure for PSVs
  • Study the effect of back pressure on PSV sizing
  • Calculate inlet pipe pressure drop for PSVs
  • Workshop: Setup the inlet piping pressure drop and sizing calculation for PSV

Add New Plant to an Existing Design
  • Determine if a new plant flare header can be tied into an existing flare system
  • Use Aspen Flare System Analyzer to evaluate the feasibility of a combined flare option.
  • Workshop: Modifying an Existing Design - Evaluating the tie in feasibility of a new plant to an existing flare system.

Troubleshooting Models
  • Review flow sheet variables for messages
  • Cleanup the components and correct selection of methods
  • Review error messages for flash failure and make corrective actions
  • Review error messages for the flow problems due to high flow rate or flow restrictions
  • Review constraints and make sound engineering judgment
  • Workshop: Take corrective action to resolve solver messages  

Using the Export/Import Functions
  • Identify and explain the export and import options in Aspen Flare System Analyzer
  • Merge multiple Flare System Analyzer files in to one single file
  • Import data from a process simulation program
  • Workshop: Using the Export/Import Wizards - Merging two or more models or sections of a model into a larger model.

Reporting in Aspen Flare System Analyzer
  • Evaluate ways to customize and format results reporting
  • Use VB automation to customize model reports for pressure flow summary
  • Become familiar with common Aspen Flare System Analyzer and Excel objects
  • Customize report using Excel Macro
  • Workshop: Add customized reports to a flow sheet simulation model

Discussion on Additional Topics
  • Learn the best practices for flare network design
  • Understand Static Pressure and Total pressure
  • Review energy balance crossing the valve
  • Evaluate the effect of Kinetic Energy term on enthalpy calculation
  • Review Mach number, Noise and RhoV2 calculations
  • Workshop: Group Discussion on Student’s Query, conclusion and wrap up

Aspen Technology, Inc. awards Continuing Education Units (CEUs) for training classes conducted by our organization. One CEU is granted for every 10 hours of class participation.