Purging / Inerting

General Description

Purging is used to remove unwanted gases from the freeboard space of a vessel. It is accomplished by applying pressure with an inert gas and then venting to atmosphere, or by pulling vacuum and filling with inert gas, or by a combination of the above that involves pulling vacuum, filling with inert gas up to a pressure above atmospheric, and venting to the atmosphere. The model of this operation can handle all three modes of operation.

This operation may result in VOC emissions if volatile compounds are present in the vessel; for more details, see Chapter 10  (Emissions).

Unit Procedure Availability

      Batch Vessel Procedure in a Reactor

      Batch Vessel Procedure in a Seed Reactor

      Batch Vessel Procedure in a Bioreactor

      Batch Vessel Procedure in a Seed Bioreactor

      Batch Vessel Procedure in a Disposable Bioreactor

      Batch Vessel Procedure in a Disposable Seed Bioreactor

      Batch Vessel Procedure in a Fermentor

      Batch Vessel Procedure in a Seed Fermentor

      Batch Vessel Procedure in a Disposable Bioreactor

      Inoculum Preparation Procedure in a Rocking Bioreactor

      Inoculum Preparation Procedure in a Roller Bottle

      Inoculum Preparation Procedure in a T-Flask

      Inoculum Preparation Procedure in a Shake Flask

      Inoculum Preparation Procedure in a Test Tube

      Nutsche Filtration Procedure

      Centrifugation in a Basket Centrifuge (Top Discharge) Procedure

      Centrifugation in a Basket Centrifuge (Bottom Discharge) Procedure

      Batch Storage in a Blending Tank Procedure

      Batch Storage in a Flat Bottom Tank Procedure

      Batch Storage in a Receiver Tank Procedure

      Batch Storage in a Horizontal Tank Procedure

      Batch Storage in a Vertical-on-Legs Tank Procedure

      Batch Storage in a Drum Procedure

      Batch Storage in a Disposable Generic Container Procedure

      Batch 1x1 Generic Box Procedure

      Batch 3x3 Generic Box Procedure

      Batch 5x5 Generic Box Procedure

      Batch 10x10 Generic Box Procedure

Purging / Inerting: Modeling Assumptions & Constraints

You may choose among three different purge type options:

      Pressure

      Vacuum

      Vacuum and Pressure

In the case of pressure purge, first pressure is applied with an inert gas to increase the system’s pressure from ‘initial’ to ‘high’, and then venting is applied to reduce the system’s pressure from ‘high’ to ‘final’.

In the case of vacuum purge, first a vacuum is produced by means of a vacuum pump to reduce the pressure in the vessel from ‘initial’ to ‘low’, and then the vessel is filled with inert gas up to a ‘final’ pressure.

In the case of vacuum and pressure purge, first a vacuum is produced by means of a vacuum pump to reduce the pressure of the vessel from ‘initial’ to ‘low’, then the vessel is filled with inert gas until a ‘high’ pressure is reached, and then venting is applied to reduce the system’s pressure from ‘high’ to ‘final’.

This cycle can be repeated several times (the number is specified by the user).

The amount of inert gas that is required for the operation is estimated by assuming ideal gas behavior.

Vacuum Pump Power Consumption

To account for the power consumption of the vacuum pump required to reduce the pressure from ambient to ‘low’ in the case of vacuum purging or vacuum and pressure purging, you may specify the vacuum pump power consumption through the Vent/Emissions tab, or you may click on the Setup button to open the Vacuum Pump Power Consumption Dialog and choose a different specification option for the vacuum pump power, such as the option to calculate the power consumption based on a suitable compression model.

In addition, you may specify a vacuum pump (as an auxiliary equipment) (optional) to account for the vacuum pump’s capital and operating costs and to consider the vacuum pump in scheduling calculations.

For more details, see Vacuum Pump Auxiliary Equipment Calculations.

Purging / Inerting: Interface

The interface of this operation has the following tabs:

      Oper. Cond’s, see Purging / Inerting: Oper. Conds Tab

      Vent/Emissions, see Vessel Operations: Vent/Emissions Tab

      Labor, etc, see Operations Dialog: Labor etc. Tab

      Description, see Operations Dialog: Description Tab

      Batch Sheet, see Operations Dialog: Batch Sheet Tab

      Scheduling, see Operations Dialog: Scheduling Tab