Ultra High Purity Nitrogen Plant with 2 ppm Oxygen Output

Why Purity Class Changes the Machine

A PSA machine makes 99.9995% nitrogen by adsorbing oxygen out of a fast cycle. A cryogenic KDN train makes ≤2 ppm by collapsing air to liquid and walking the distillation column's temperature profile until oxygen is physically held back below trace levels. Different physics, different guarantees, different consequences when someone overspecs - or underspecs - the duty.

The spec this family serves is written in ppm: ≤2 ppm oxygen in the product, helium and neon (the noble gases that no chemical trick removes, only cryogenic fractionation) held at ≤25 ppm. Electronics-grade and specialty-gas buyers care about the HeNe number specifically because nobles are permanent impurities - diluents forever in the gas. Once the certificate says ≤25 ppm HeNe, your downstream process can stop worrying.

Inside a KDN Train

• Air compressor and pre-cooling system - feed air prepared for a cryogenic life.
• Molecular sieve purification - water, CO₂ and hydrocarbons scrubbed to parts-per-million, because the cold box will trap whatever survives and then tell everyone about it.
• Fractionation tower system - nitrogen's lower boiling point lifts it away from liquid oxygen held at the column bottom; packed sections and precise reflux engineering are where the 2 ppm spec is actually won.
• Nitrogen compression system - product gas pressurized to your 0.25–0.7 MPa spec.
• DCS instrument control - analyzer loops on oxygen, humidity and hydrocarbons with interlocks; the plant's brain, watched in our remote monitoring service.

Reference Duty Points

Where 2 ppm Nitrogen Is Non-Negotiable

Polysilicon and electronics - dopant chemistry doesn't tolerate oxygen at any ppm you can name. Chemical fibers and caprolactam - polymerization catalysts poisoned by trace O₂. Oil and gas tank farms - blanketing that must also pass HeNe limits for downstream reuse. Metal powders and Rare-earth reduction - furnaces where oxygen picks the metal right back out. And specialty gas blenders who buy the KDN stream as the base of everything else they bottle.

Oxygen Coproduct: the Quiet Second Revenue Line

Distillation that strips nitrogen of oxygen *concentrates* oxygen somewhere. Sized as a coproduct, that 99.6% oxygen stream - 12 tons a day on a KDN-3000, more on larger trains - is either sold, used on site, or carefully vented. We simulate the trade-off with you because the O₂ tap changes column internals; bolt it on later and it costs multiples. Decide at design review, not at commissioning.

Cryogenic Credentials Behind the Purity Promise

The purity numbers above mean nothing without the factory record that makes them repeatable: nearly 300 ASU projects, high-efficiency packing in our own cold-box design, A1/A2 license weld radiography, DCS sequences with analyzer interlocks tested in factory simulation. Purity at design point is the easy half of this business; purity in month thirty is the engineering. Our plants get audited on the second half, and the reference list keeps answering.

FAQ

Why 99.999% PSA Nitrogen Still Fails These Processes

A KYPN PSA machine can honest-to-goodness deliver 99.9995% nitrogen - five nines, decimal point and all. So why do chemical fiber lines, polysilicon reactors and electronic-grade processes keep buying cryogenic plants and paying for a distillation column to chase the last two parts per million?

Three reasons, and each one is a chemistry story, not a marketing story. First, oxygen at ppm level behaves differently than at percent level. PSA economics stop at single-digit ppm oxygen; below roughly 5 ppm the adsorption selectivity game gets brutal and the polish beds get expensive and fragile. A cryogenic column simply does not have that problem - the distillation split drives oxygen down to the 2 ppm contract level and holds it there, not as a race against sieve saturation. Second, helium and neon do not care about your sieve. Inert impurities pass straight through any PSA machine. Our KDN deep-purification train removes them to ≤25 ppm combined; if your catalyst sees He/Ne and dies, only the cryogenic route saves you. Third, steady beats spectacular. Chemical plants run three shifts for years; a cryogenic plant's ppm spec on day 400 looks like its spec on day 40, while a PSA plant's spec tracks its sieve health, valve leak-down and summer ambient.

The Deep Purification Train, Section By Section

Everything that defines this product happens downstream of the main cold box:

• Oxygen removal. Product nitrogen passes a heated catalytic deoxo stage where trace oxygen combines with injected hydrogen over a palladium catalyst, then a molecular sieve bed absorbs the resulting water. The stage is designed with margin on the deoxo bed because that margin is your 2 ppm guarantee.
• Carbon dioxide and moisture. Dual-purpose molecular sieve beds, heat-regenerated, with switching logic that never lets the bed breakthrough silently - analyzers downstream interlock the product line.
• Hydrocarbon residual. Where the process cares (and polysilicon cares), the feed-air siting study from day one is what protects you here - no purification train wants a solvent-plant intake next door.
• Analysis as part of the machine. Trace oxygen to single-digit ppm and moisture analyzers ship in the package, not as an options-list add-on, because the plant's contract purity is unprovable without them.

Sizing The Duty And Making The Numbers Talk

A KDN ultra-nitrogen plant is quoted from five inputs: flow in Nm³/h, oxygen ceiling in ppm, He/Ne ceiling if your process needs one, delivery pressure in the 0.25-0.7 MPa band, and the site's climate and grid. Chemical fiber owners usually also want a liquid nitrogen provision for peak events; that is a tank-and-vaporizer line item and we price it into the same plot plan.

The decision arithmetic is worth putting on paper. If your process can genuinely tolerate 10 ppm and your electricity is cheap, a PSA with polish may be the honest answer and we will say so. If a single oxygen excursion costs a reactor campaign - and in polysilicon one excursion costs a campaign - then the cryogenic plant's flatline ppm behavior is the product, and the capital premium is the insurance premium. We have sold both outcomes to different plants in the same industry, because the honest answer depends on your cost-of-failure, not our preference.

Send the five inputs; the study comes back with flow diagram, energy estimate and the honest technology verdict. That verdict has talked owners out of more overspec plants than it has sold - and built the reputation that keeps them sending us the next one.