Introduction to Nitrogen Generators for Heat Treatment Furnaces

Nitrogen generators are widely used in various gas industries and are highly favored by manufacturers during the production process. Their main principle involves using high-quality imported carbon molecular sieve as the adsorbent and employing the pressure swing adsorption (PSA) method at room temperature to separate air and extract high-purity nitrogen. The extracted nitrogen, due to its chemically inert and non-combustible properties, is extensively applied in the heat treatment industry. Heat treatment refers to the collective term for processes such as heating, insulation, and cooling of metal materials in the metallurgical industry. So, what role does a nitrogen generator play in the heat treatment industry?

Functions of Nitrogen Generators for Heat Treatment Furnaces

Preventing Oxidation

The nitrogen produced by nitrogen generators can prevent oxidation of equipment during metal heat treatment. Since metal heat treatment involves heating metals, the processed gases may oxidize. Adding nitrogen as a protective gas can prevent oxidation of the equipment and extend its service life.

It can also significantly prevent metal corrosion in the air. Since corrosion is a chemical property of oxidation, incorporating nitrogen into the protective gas during post-weld heat treatment significantly affects the pitting resistance of metal materials. Balancing the nitrogen content and the properties of the metal materials in the weld metal and heat-affected zone is crucial, as corrosion resistance decreases with increasing nitrogen content.

Nitrogen Dilution

Nitrogen produced by nitrogen generators has many applications in industrial furnaces. Research shows that nitrogen greatly impacts flame stability. Due to the diffusive thermal characteristics of fuel and air mixtures, adding nitrogen can promote flame extinction [10]. Introducing a diluent gas into the fuel stream is effective for reducing flame temperature, leading to a decrease in thermal NOx (nitrogen oxides) production.

Nitrogen in nitrogen generators is also a key factor in suppressing soot formation in flames. It removes the thermal energy required for soot growth, and adding nitrogen reduces the concentration of polycyclic aromatic hydrocarbon precursors. The relative impact of dilution decreases as the molar fraction of nitrogen increases.

Nitrogen Cooling

The nitrogen produced by nitrogen generators can also be used for cooling. In the coal mining industry, nitrogen is widely applied, primarily because coal is highly flammable and prone to spontaneous combustion, which can lead to major accidents. Adding nitrogen can cool coal mines, making combustion less likely.

Most coal mines in China are equipped with underground mobile nitrogen generators or high-flow ground nitrogen production units. The purpose of nitrogen injection is to reduce the oxygen concentration in the oxidation zone of the goaf to below 6%, creating an environment where coal no longer oxidizes. When coal temperatures rise, the effect of nitrogen injection lowers the temperature, creating a cooling effect and significantly improving the success rate of fire prevention.

The above outlines the roles of nitrogen generators in heat treatment. They primarily have significant effects in preventing oxidation, nitrogen dilution, and nitrogen cooling. They are not only applied in the metal industry but also play crucial roles in industrial furnaces and nitrogen cooling. In the increasingly developing industrial sector, nitrogen generators serve both key auxiliary and leading roles. Manufacturers should focus on understanding their functions when selecting appropriate nitrogen generator equipment.