Ground Freezing in Underground Construction
In underground engineering projects, soil conditions vary significantly in terms of softness and bearing capacity. Freezing the ground is often required before construction can commence. Traditional methods utilize ammonia or brine freezing, a century-old technique. However, ammonia freezing demands stringent management of liquid ammonia, with any lapses potentially leading to accidents during storage, transportation, or usage.

Liquid nitrogen (LN₂) freezing represents an emerging technology with distinct advantages:

Simplified System: Fewer components compared to conventional ammonia/brine systems
Ultra-Low Temperature: Reaches -196°C, enabling rapid freezing (10× faster than traditional methods)
Safety & Efficiency: Eliminates risks associated with hazardous chemicals
First adopted in developed countries around 1960, LN₂ freezing has proven invaluable in:

Urban underground projects (e.g., subways in congested areas)
Mine construction
Emergency structural stabilization
China began integrating LN₂ freezing in the 1990s for projects like the Shanghai Metro. Initially, hybrid systems combining conventional and LN₂ freezing were used to reduce costs. As LN₂ prices declined, full LN₂ solutions gained traction, offering faster ground stabilization and enabling construction in challenging geological conditions.

Fire Prevention & Suppression
LN₂'s ultra-low temperature (-196°C), inert nature, and eco-friendliness make it highly effective for fire control, albeit at a higher cost compared to conventional agents. Key applications include:

Coal Mine Fires: LN₂ has been successfully deployed in multiple coal mine incidents, becoming a critical tool for combating underground conflagrations.
Specialized Fire Extinguishers: Compact LN₂ units are now used in laboratories, archives, and other critical facilities, offering superior fire suppression despite shorter shelf life limitations.
Keweijiani - Your Partner in Cryogenic Innovation
As a dedicated developer of LN₂ equipment, Keweijiani welcomes collaborations to advance LN₂ applications across industries. Together, we can unlock the full potential of this transformative technology.