What is Nitrogen Purging & How Does it Work?

In many industrial processes, maintaining a moisture-sensitive and oxygen-deficient environment is paramount to ensure the quality of their final products is not altered. The challenges posed by potential damage from water vapor and oxidation are prevalent concerns for many industrial manufacturers.

To tackle these problems, nitrogen purging is routinely incorporated into relevant processes.

What Is Nitrogen Purging?

Nitrogen purging is a process used to remove undesirable or hazardous substances from a system or container by replacing the existing atmosphere with nitrogen gas. This technique is particularly common in industries such as oil and gas, electronics manufacturing, and food packaging.

The primary objectives of N2 purging include:

• Inerting: Nitrogen is an inert gas, meaning it does not react with other substances. By purging with nitrogen, oxygen, and other reactive gases are displaced, reducing the risk of combustion or oxidation in certain environments.
• Oxygen Removal: In oxygen-sensitive processes or storage, N2 purging helps eliminate oxygen, preventing corrosion, degradation, or unwanted chemical reactions.
• Moisture Control: Nitrogen is dry, and purging with it helps control moisture levels, minimizing the potential for rust, mold, or other moisture-related issues.
• Contaminant Removal: By replacing the atmosphere with nitrogen, unwanted contaminants or impurities are flushed out, ensuring a clean and controlled environment.

The process involves introducing nitrogen into the system or container, gradually displacing the existing air or gases. The displaced air is typically vented, leaving behind a nitrogen-rich environment. N2 purging is a valuable technique for enhancing safety, preserving product quality, and maintaining optimal conditions in various industrial applications.

Why Nitrogen Purging is Necessary

The benefits of N2 purging are numerous, but the most crucial reasons for nitrogen gas purging are to prevent chemical alteration of products and to prevent moisture-related equipment damage or even combustion.

A lot of industrial manufacturing processes could be adversely affected when conducted in the presence of moisture or oxygen-rich air. The oxidative damage caused by these unwanted impurities will diminish the quality of the final products with costly implications for profitability. Oxygen-sensitive operations integrate nitrogen gas purging equipment to prevent unfavorable manufacturing conditions.

Common Applications of Nitrogen Purging Systems

Nitrogen gas purging is currently being used across a range of industrial manufacturing processes, and purging is one of the reasons the industrial use of nitrogen is so common. Outlined below are some key uses of nitrogen flushing procedures in different applications.

• Nitrogen blanketing for ships, tankers, and potentially combustible environments
• Brewery purging headspaces to extend the shelf life of beer
• Nitrogen purging for transformers and volatile electrical environments
• Purging organic compounds in the chemical/petrochemical industries
• Pipeline drying and purging to limit oxygen concentrations – learn more about NiGen’s pipeline maintenance services.
• Toxic gas elimination in process chambers (e.g., sputtering tools)
• Modified Atmosphere Packaging with food-grade nitrogen in food production and packaging plants to remove moisture, oxygen, and other gaseous impurities
• Metal fabrication where N2 purging systems are used to eliminate compounds that might affect weld quality

Four Types of Nitrogen Purging Systems

There are various N2 purging systems, and the choice depends on specific operational needs. Below, we describe four key types of nitrogen purging systems:

1. Displacement Purging with Nitrogen Gas: Ideal for equipment with straightforward cross-sections, like pipelines. The process involves using a cleaning component called a “pig,” which is propelled through the equipment’s lumen using pressurized nitrogen gas. This purges the interior, removing gaseous and particulate impurities.
2. Dilution Purging with Nitrogen Gas: Involves mixing gaseous nitrogen with the gas to be eliminated, and the mixture is then expelled through an outlet point far from the gas inlet. Effective for both simple and complex systems, such as kilns, reactors, and columns.
3. Pressure Liquid Transfer: Useful for systems with space constraints, this method allows the transfer of liquids without an external pump. Pressurized nitrogen gas drives fluid motion, pressurizing the headspace and purging the vessel. This minimizes the risk of oxidation during liquid transfer between two process tanks.
4. Pressure-Hold Vacuum Method: Applied to equipment with a single vent, this method pressurizes vessels with nitrogen. After the vessel’s contents combine with pressurized nitrogen, dilution and venting follow. The process is repeated as needed to achieve a satisfactory purge level.

Nitrogen Purging in Pipelines

Pipeline purging with nitrogen gas is a critical component of natural gas line commissioning for flow lines. This procedure is necessary to eliminate oxygen, water vapor, and other impurities that are retained within a newly laid pipeline network. Failure to eliminate these substances will alter the quality of fluids being transported through the flow lines.

N2 purging is a pretty straightforward procedure where the pressurized gas is forced through the lumen of the selected pipelines forcing out all gaseous and particulate impurities.

Pipeline Purging Safety Tips

Conducting N2 purging in an industrial setting comes with inherent risks. To ensure the safe execution of pipeline purging, operators should adhere to the following concise steps:

• Ensure meticulous instruments/apparatus handling
• Properly train and brief all personnel on how to safely perform their duties
• Designate emergency protocols for shut down and personnel evacuation with the provision of multiple points of egress
• Mandatory use of personal protective equipment by all personnel involved in purging operations

NiGen Offers Trusted Nitrogen Purging Services

Over the last decades, NiGen has been providing the very best nitrogen generation solutions suited to various industrial process needs. We offer cost-effective on-site nitrogen generators to a broad range of industries. If your needs are temporary, ask us about our nitrogen generator rentals.

Contact us today for a quote or specifications about our products and services.