Challenge:
A plastics manufacturer’s research and development facility needed a continuous and reliable nitrogen supply to operate its nuclear magnetic resonance (NMR) equipment to determine the polymer’s compositional analysis. One of the lab’s NMR machines uses a cryogenic probe operating near -200°C, making ultra-dry, oxygen-free nitrogen critical. Any oxygen contamination would compromise test results, and even trace moisture would freeze and clog the probe.
The traditional solution—liquid nitrogen Dewar tanks—posed serious drawbacks:
- High consumption: At 16.8 CFM flow, the lab would consume the usable contents of a Dewar in just 4–5 hours. Meeting continuous demand would require 2 Dewar tanks per day for an 8 hour shift.
- Logistical burden: Frequent tank changeouts, storage limitations, and labor for handling numerous heavy (95 pounds when full) cryogenic cylinders.
- Space and permitting issues: The lab’s urban site lacked room for a permanent bulk tank system, and prior attempts at permitting a storage area were denied.
- Waste and cost: Each Dewar loses ~15% of its nitrogen to boil-off. Combined with delivery fees and rental charges, liquid nitrogen cost the lab around $3 per cubic foot.
- Reliability risks: The lab had experiences supply interruptions due to delivery truck breakdowns and driver shortages in the past and wanted to alleviate that concern with in-house nitrogen generation.
The lab needed a solution that eliminated these operational risks while guaranteeing reliable and consistent purity and dryness for sensitive R&D testing.
Solution:
The lab’s maintenance lead contacted MCE’s compressed air experts based on their industry reputation. Diversified Air designed and commissioned a Mikropor MNG US 150 nitrogen generator that leveraged the lab’s existing compressed air system. This Pressure Swing Adsorption (PSA) type Nitrogen Generation system is used to separate and enrich Nitrogen from Oxygen and uses a CMS (Carbon Molecular Sieve) for adsorbent. This is especially useful for industries that require the highest levels of Nitrogen purity by the most cost-effective means possible.
Key system features:
- Flow & Purity: 16.8 CFM at 68°F, consistently delivering 99.8–99.9% purity (above the required 97%).
- Dryness: Exceeds the required -50°F dew point, often achieving -60°F to -80°F, ensuring zero condensation or icing at cryogenic probe temperatures.
- Compact footprint: Fits within ~7 ft², with two 120-gallon buffer tanks for stable PSA operation.
- Ease of Commissioning: Commissioning was straightforward, requiring only minimal prep work to install. No special permitting, bulk tank infrastructure, or complex site modifications needed.
- Monitoring: Integrated dew point monitor for continuous visibility, with alarm and logging options.
- Simple maintenance: Only requires annual filter changes.
Because the lab already had three (3) 15 HP compressors with surplus capacity, the nitrogen generator could operate without requiring new compressors or dryers. This kept capital costs low while ensuring a self-sufficient nitrogen supply.
Results:
- Consistent Research Performance: The generator continuously exceeds purity and dew point specifications, supporting reliable NMR operation.
- Operational Reliability: Freed the lab from supplier schedules, truck delays, and nitrogen shortages.
- Safety & Space Savings: Removed the need to handle heavy cryogenic tanks, reducing risk of employee injuries and avoided permitting issues for bulk storage.
- Low Maintenance: Minimal upkeep—annual filter changes only.
- Quick Installation & Commissioning: MCE’s team handled specification, setup, and commissioning smoothly, with the system running reliably since installation.
Cost Savings:
- Lab’s Nitrogen Usage: 16.8 CFM for an 8-hour workday ~8,064 cu ft of nitrogen per day
- Annual Operation: at 250 work days annually ~2,000 hours
- Annual Nitrogen Need: 16.1 million cu ft
Cost Comparison
- Dewar delivery (~$1.50/100 cu ft): $2.4 million per year
- Nitrogen generator (~$0.20/100 cu ft): $322,000 per year
- Annual Savings: $2.08 million
Result: On-site nitrogen generation returned its purchase value in less than 6 months and saves the lab over $2.08 million per year while eliminating delivery, rental, and waste.
Conclusion:
By installing a nitrogen generator, the research labs gained autonomy, reliability, and cost savings while ensuring their plastics R&D applications have a steady supply of high-purity, dry nitrogen. The MCE team’s ability to evaluate facility requirements, leverage existing air infrastructure, and provide ongoing support made the project a long-term success.