Wilhelmsen Ships Equipment has been a major supplier of Nitrogen Inert Gas Systems based on Hollow Fibre Membrane technology since the late 1980’s.  Hundreds of systems ranging from small topping up generators to large total inert gas systems have been installed on a wide range of ships that require a clean, dry inert gas, either for maintaining a non-explosive atmosphere in the cargo tanks or for preservation of cargo quality, and for gas carriers requiring protection of insulation from damage by icing. Major operators of Chemical tankers, Gas Tankers, Offshore Supply Ships and reefers enjoy the reliability and high performance of the Unitor Nitrogen Inert Gas Systems.  

Wilhelmsen Ships Equipment has a standard range of Nitrogen generators from 10 m3/h to 5000+ m3/h with a capability of providing Nitrogen with a purity ranging from 99,9% to 95% dependant on the application and requirement. 

Systems designed for large volumes at low purities will deliver superior air recovery performance of nitrogen at  high purities. Wilhelmsen Ships Equipment's generators can produce nitrogen with a dewpoint down to –70oC,   as has been proven by extensive, Class-witnessed testing.  

Features and benefits

High N2 production effectiveness, 53% at 95% N2 Purity range, 95 – 99.9 volume % N2. -70°C dew point after expansion  to atmosphere pressure PLC control of Nitrogen Generator parameters Auto-ventilation prevents off-spec gas from being delivered to the process. Silent, unattended operation Sophisticated feed air treatment arrangement Long life of membrane module. Engineering and class approvals Easy to install, operate and maintain. A full range of standardised components provides flexibility to meet the customers’ individual demands. Indoor, outdoor or containerized locations Applying most advanced fiber technology

 Technical Design  

To make up a complete Nitrogen Membrane Inert Gas System, compressed air normally has to be provided from dedicated air compressor(s). The productivity of the membranes improves at increased pressure and a typical membrane system will operate most effectively at about 14bar(g) air supply. The 14 bar air can be provided by normal industrial type oil lubricated screw compressors.

 By using compressors with modulating control the pressure can be maintained constant, independent of the air flow requirement. This air will be saturated with water and contaminated by traces of oil and particulates. A feed air treatment system is required to provide clean air free from particles and oil. This clean air will allow for a high quality nitrogen product, free of contaminants, and will ensure long life of the membrane system.

 The air separation system consists of parallel sets of membrane modules. The Nitrogen leaves at essentially the same pressure as the entering air.

The oxygen-enriched flow is directed to permeate discharge at atmospheric pressure and is to be vented to a safe area. Down stream of the membranes, a pressure control valve is designed to keep the membrane system at a pre-adjusted constant pressure. This control valve is operated manually or automatically by using the analogue signal from the oxygen analyser(s) that will provide automatic oxygen control. Depending on the application, the nitrogen can be delivered directly to the protected space or stored in a receiver tank.

 A high-pressure booster compressor can be included to provide nitrogen at higher pressures, such as for recharging of nitrogen cylinders.