LIN-Assist Plants

LIN-assist plants use a simplified cryogenic separation cycle that eliminates mechanical refrigeration equipment and replaces it with injection of a small amount of liquid nitrogen.  The vaporizing liquid provides the refrigeration required for air separation and nitrogen purification.  Typically, more than 95% of the plant product is freshly-produced gaseous nitrogen, with the remainder vaporized liquid. 

Where there is a good match between rated plant capacity and user demand, when user demand is relatively steady, and when product in not required at more than about 100 psig (7 Barg), LIN-assist plants will produce product more economically than 100% liquid vaporization.  When demand varies considerably and high purity product is required, liquid nitrogen vaporization may continue to be the preferred choice for at least some of the site demand. 

The LIN-assist nitrogen production process is similar to that used in conventional cryogenic nitrogen plants.  The only significant difference is that LIN import and vaporization is used to provide the refrigeration necessary to cryogenically separate air by low temperature distillation and purify the product instead of a mechanical refrigeration cycle. (Your liquid nitrogen supplier uses a large scale mechanical refrigeration system in the plant that is used to produce the liquid used at your site.)  Typically, when producing at a relatively constant rate near its rated capacity, 20 to 30 units of gaseous nitrogen can be produced by the plant for every unit of LIN consumed. 

LIN-assist plants are inherently reliable, as they have less mechanical equipment than a conventional cryogenic plant and most components run at continuous steady-state conditions. LIN storage and vaporization is an inherent part of the system. Vaporized LIN is automatically provided to meet short-term demand peaks and back up the air separation process.

Features:

• Produce up to 1000 Nm3/hr of gaseous nitrogen
• LIN usage is less than 5% of product flow
• Low specific power – 0.30 kwh / Nm³ of product
• No cooling water required
• Simple process with few major components
• Screw compressors
• Molecular sieve air purification
• Cold box housing cryogenic distillation system
• LIN storage tank
• Ambient vaporizers
• Runs unattended with advanced monitoring and control system
• LIN supplies demand peaks and emergency backup 
• Modular design for compact arrangement and rapid installation
• Advanced control features permit unattended operation, remote diagnostic monitoring and troubleshooting.

Model

GAN Production  (Nm³/hr) Minimum

Production Maximum

Purity
Volume %

Pressure Bar (g)

Model

GAN Production  (SCFH) Minimum

Production Maximum

Purity
Volume %

Pressure Psig

Plants based on LIN-assist technology not only compete compete against 100% vaporized LIN, but also against non-cryogenic separation processes; especially in the lower production rate end of the application range.  Non-cryogenic processes are most attractive when nitrogen purity may be lower than "LIN purity" (e.g. 98 to 99.5% is sufficiently pure).

At the higher end of the range, LIN-assist competes against convention cryogenic separation processes. 

When choosing a system that is expected to be your nitrogen source for many years, the selection process must not only reflect current costs for power and liquid nitrogen, and current usage rates and patterns, but future expectations regarding how these important variables may change. In most cases, more than one technology could be a reasonable choice. 

UIG wants to help you select and install the best choice for your particular situation.