Manufacturer and supplier of air separation plants, engineering, field services, and on-site produced nitrogen and oxygen.

LIN-Assist Plants

LIN-assist plants offer a compact, reliable and cost effective alternative to vaporized liquid for some nitrogen users, in particular, those that have relatively steady demand rates between about 15,000 SCFH to 40,000 SCFH. 

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. 

LIN-assist plants can produce gaseous nitrogen for less than half the cost of liquid nitrogen (LIN) when demand is relatively steady.  The actual savings, versus 100% LIN vaporization, will depend upon the match between plant capacity and peak user demand (similar flow rates are best), user demand pattern (24/7 at steady rates is best), local power cost, and length of supply contract (shorter contracts require higher annual capital cost amortization). 

If user demand is relatively low, and variable, either a traditional liquid supply may be more appropriate, or, if nitrogen purity is not a critical parameter, a non-cryogenic system might be the most economical supply source.  See the graphic on this page.

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. 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. LIN-assist plants are compact units requiring very little area to install.



  • 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
  • Run 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.


GAN Production  (Nm3/hr) Minimum

Production Maximum

Volume %

Pressure Bar (g)

ULAP    750  500  800 < 10 ppm O2 7
ULAP  1000 700 1,050 < 10 ppm O2 7


GAN Production  (SCFH) Minimum

Production Maximum

Volume %

Pressure Psig

ULAP    750 19,000 30,500  < 10 ppm O2 100
ULAP  1000 26,500 40,000 < 10 ppm O2 100


Plants based on LIN-assist technology offer savings compared to using 100% vaporized LIN.  They are one of several potential supply options, 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. 

Many factors enter into selection of the best technology choice in the capacity range where LIN-assist plants are a possible technology choice.  UIG will examine your situation, including your current requirements and your expectations regarding future changes.

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.

Universal Industrial Gases, Inc.
Universal Cryo Gas, LLC
3001 Emrick Blvd., Suite 320
Bethlehem, Pennsylvania 18020 USA

Phone (610) 559-7967 Fax (610) 515-0945

All material contained herein Copyright 2003 - 2015 UIG.