Content area
Full Text
Pressure swing adsorption (PSA) can be a cost-effective method of onsite nitrogen generation for a wide range of purity and flow requirements.
Nitrogen gas is a staple of the chemical industry. Because it is an inert gas, nitrogen is suitable for a wide range of applications covering various aspects of chemical manufacturing, processing, handling, and shipping. Due to its low reactivity, nitrogen is an excellent blanketing and purging gas that can be used to protect valuable products from harmful contaminants. It also enables the safe storage and use of flammable compounds, and can help prevent combustible dust explosions. Nitrogen gas can be used to remove contaminants from process streams through methods such as stripping and sparging.
Because of the widespread and growing use of nitrogen in the chemical process industries (CPI), industrial gas companies have been continually improving methods of nitrogen production and supply to make them more efficient, costeffective, and convenient for chemical processors. Multiple nitrogen technologies and supply modes now exist to meet a range of specifications, including purity, usage pattern, portability, footprint, and power consumption. Choosing among supply options can be a challenge. Onsite nitrogen generators, such as pressure swing adsorption (PSA) or membrane systems, can be more cost-effective than traditional cryogenic distillation or stored liquid nitrogen, particularly if an extremely high purity (e.g., 99.9999%) is not required.
Generating nitrogen gas
Industrial nitrogen gas can be produced by either cryogenic fractional distillation of liquefied air, or separation of gaseous air using adsorption or permeation. German engineer Carl von Linde developed cryogenic distillation of air, the oldest method of nitrogen production, in 1895 (J). Cryogenic distillation is still used today in large commercial air separation plants, and accounts for nearly 65-70% of the total nitrogen production (2).
Leonard Pool (the founder of Air Products) introduced the concept of generating industrial gases onsite in the early 1940s. Onsite cryogenic plants were built on or near the user's site, and the product was delivered by pipeline. This method provided a low-cost, reliable supply for large-volume users of industrial gases. However, due to the relatively high capital and power costs associated with onsite cryogenic plants, smaller-volume users were typically limited to liquid nitrogen supply delivered by vacuum-insulated trucks. The stored liquid nitrogen was vaporized and...