• Introduction

• Global parameters

• Products

• FID conversion

• Canalised emissions

• Storage tank

• Material loading

• Heat variation

• Distillation

• Evaporation

• Purge/Gas sweep
• Empty vessel
• Partially filled

• Depressurisation

• Average factors

• Ranges factors

• Correlation factors

Purge/Gas sweep models

Purging operations are usually realised on industrial units (tank, reactor, etc.) in order to maintain product quality (e.g., by using a dry sweep gas to minimise water vapour in system), to reduce concentrations of flammable vapours or also to purge all residual vapour from an installation.

Purge/gas sweep operations are realised:

• By direct injection of a gas (nitrogen, air or other) in the installation,
• By forced extraction (canalised output) of vapours.

Following picture present reactors with forced extractions (used for purging the headspace in order to maintain vapour concentration below the inferior explosive limit):

In order to evaluate atmospheric emissions during purging operations, Envmodels propose two calculation tools:

• One model for empty installation purging (only residual solvent vapours are present),
• One model for partially filled installation purging (that still contain liquid solvents).