Cryogenic air separation unit (500 t/d GOX)

Double-column cryogenic air separation without argon column, producing 500 t/d gaseous oxygen at 30 barg and 10,000 Nm3/h pipeline nitrogen, with LOX/LIN backup storage.

Calculation maturity: BalancedDesign maturity: Screening (research)Not independently reviewedAir separationIndustrial gasesCryogenic separationReport a problem with this process
Research outputNot engineering advice and not an approved design: do not use it for construction, operation or safety decisions. What this means

ASU-1 separates atmospheric air in a double-column cold box. The main air compressor and a direct-contact aftercooler feed a temperature-swing adsorption front end that removes water, CO2 and hydrocarbons. A booster-braked expander provides refrigeration, with Lachmann air to the low-pressure column. Products are GOX >= 99.5 mol% O2, compressed to 30 barg for a pipeline, and GAN <= 10 ppm O2 at 8 barg. LOX and LIN tanks with cryogenic pumps and ambient-air vaporizers back up both pipelines. There is no argon column; argon leaves with the waste nitrogen.

All flows, pressures and duties are concept estimates (about +/-30 %); see the design basis and DESIGN.md in the engineering files for every assumption.

Capacity
500 t/d GOX (14,600 Nm3/h) and 10,000 Nm3/h GAN; LOX and LIN 600 kg/h each
Operation
8,400 h/a
Location
Assumed coastal industrial site
Automated checks
6 of 6 pass (Basic engineering gates)
Maintainers
Artur Schweidtmann
Design basis and assumptions (7)
  • ASSUMED O2 recovery ~83 % (D-066: no argon column, 99.5 % purity, GAN drawn from the HP column (13 % of the HP column air), 13 % Lachmann air; was 94 %, which the simulated double column does not reach).
  • ASSUMED MAC discharge 5.8 bara, HP column top 5.4 bara, LP column top 1.3 bara.
  • ASSUMED refrigeration by booster-braked expander, Lachmann air to the LP column, ~11,500 Nm3/h, ~198 kW (D-061); the boosted air enters the main exchanger at 15 C (D-067).
  • ASSUMED regeneration gas ~14,600 Nm3/h waste N2 (D-066), heated electrically to 200 C.
  • ASSUMED DCAC air outlet 12 C via chilled water from an N2 evaporative cooler; no mechanical chiller. All waste N2 not used for regeneration goes to the evaporative cooler; its chilled water also trims the booster air to 15 C (D-067).
  • ASSUMED GAN taken as pressurized N2 from the HP column top (~5.2 bara) and compressed to 9 bara.
  • ASSUMED all flows, pressures, duties and DNs are concept estimates, accuracy about +/-30 %.

From process/design-basis.yaml.

Engineering model

Loading the drawing…
Drawing of the process (preview)Open the engineering model

The interactive model (drawings, streams, 3D) is made for larger screens.

Snapshot of c3ab348, cheme-as-code 1.6.0.

What goes in and out

In

  • AirFeedstock85,810 Nm3/h dry CO2-free air, 85,840 Nm3/h with the CO2 (D-066), at 30 C, 1.013 bara and 80 % RH (D-058); the owner's design specification (D-099)

Out

  • OxygenMain productGOX >= 99.5 mol% O2 at 30 barg
  • NitrogenCo-productGAN <= 10 ppm O2 at 8 barg
  • OxygenCo-productLOX to backup storage
  • NitrogenCo-productLIN to backup storage
  • ArgonEmissionNot recovered: leaves with the waste nitrogen vent
  • NitrogenEmissionWaste nitrogen vent after TSA regeneration and evaporative cooling

Utilities: Electricity (6.6 kV; MAC, GOX and GAN compressors, electric regeneration heater), Cooling water (25/35 C, heat rejected)

Show in the process graph

Life cycle assessment

66.7kg CO2-eqpartial, 18 data gaps

Climate change per 1 t GOX, cradle-to-gate · de-grid: 105 · nl-grid: 88.3

Data: UK Government GHG Conversion Factors for Company Reporting 2026 (flat file) (OGL-3.0); Greenhouse gas emission intensity of electricity generation in Europe (indicator ENER038) (CC BY (version not stated) under the EEA legal notice (https://www.eea.europa.eu/en/legal-notice): re-use, including commercial, with the EEA acknowledged in each copy and the meaning not distorted). Contains public sector information licensed under the Open Government Licence v3.0 (UK Government GHG Conversion Factors for Company Reporting 2026, DESNZ). Source: European Environment Agency (EEA), indicator ENER038 'Greenhouse gas emission intensity of electricity generation in Europe' (2026), https://www.eea.europa.eu/en/analysis/indicators/greenhouse-gas-emission-intensity-of-1, CC BY; values converted from g to kg CO2e per kWh.

Partly assumed factors. Some factors are assumed; see each contribution for its source.

Main contributors
  • Electric power (6.6 kV grid supply)97.3 %
  • Cooling water return (heat rejected)1 %
  • Structural steel0.55 %
  • Carbon steel equipment0.42 %
  • Aluminium equipment0.28 %
  • 8 others0.47 %
Contributions, baseline
64.91 kg CO2-eq0.665 kg CO2-eq0.3693 kg CO2-eq0.2789 kg CO2-eq0.1854 kg CO2-eq0.09232 kg CO2-eq0.06973 kg CO2-eq0.08189 kg CO2-eq0.06136 kg CO2-eq0.008489 kg CO2-eq65.58 kg CO2-eq0.9155 kg CO2-eq0.2234 kg CO2-eq0.008489 kg CO2-eqElectric power (6.6 kV grid s…64.91 kg CO2-eqElectric power (6.6 kV grid supply): 64.91 kg CO2-eqCooling water return (heat re…0.665 kg CO2-eqCooling water return (heat rejected): 0.665 kg CO2-eqStructural steel0.3693 kg CO2-eqStructural steel: 0.3693 kg CO2-eqCarbon steel equipment0.2789 kg CO2-eqCarbon steel equipment: 0.2789 kg CO2-eqAluminium equipment0.1854 kg CO2-eqAluminium equipment: 0.1854 kg CO2-eqMaintenance: Structural steel0.09232 kg CO2-eqMaintenance: Structural steel: 0.09232 kg CO2-eqMaintenance: Carbon steel equ…0.06973 kg CO2-eqMaintenance: Carbon steel equipment: 0.06973 kg CO2-eqOther (3, construction)0.08189 kg CO2-eqOther (3, construction): 0.08189 kg CO2-eqOther (2, maintenance)0.06136 kg CO2-eqOther (2, maintenance): 0.06136 kg CO2-eqOther (1, transport)0.008489 kg CO2-eqOther (1, transport): 0.008489 kg CO2-eqOperation65.58 kg CO2-eqOperation: 65.58 kg CO2-eqConstruction0.9155 kg CO2-eqConstruction: 0.9155 kg CO2-eqMaintenance0.2234 kg CO2-eqMaintenance: 0.2234 kg CO2-eqTransport0.008489 kg CO2-eqTransport: 0.008489 kg CO2-eq1 t GOX66.72 kg CO2-eq1 t GOX: 66.72 kg CO2-eq

Each flow of the inventory into its phase, the phases into the functional unit; band widths are impacts. Hatched: a credit.

Method and data
Goal
Cradle-to-gate carbon footprint of pipeline GOX at 30 barg for the concept stage: which utilities dominate. A screening carbon footprint on open background data (UK DESNZ 2026 as a proxy for an undecided site, D-092): flows and duties are concept estimates (+/-30 %), and the flows no open factor covers are listed as gaps.
Functional unit
1 t GOX (1 t oxygen, gaseous, >= 99.5 mol%, 30 barg)
Boundary
cradle-to-gate
Allocation
exergy
Characterisation
Factors kept with the process · GWP100 (DESNZ 2026: AR4/AR5; direct emissions: IPCC 2021)
Data quality
Partly assumed factors
Result
partial screening carbon footprint · 18 data gaps
Data sources

UK Government GHG Conversion Factors for Company Reporting 2026 (flat file) (UK Department for Energy Security and Net Zero (DESNZ)) · 2026 v1.2 (flat file republished 2026-07-31) · OGL-3.0Contains public sector information licensed under the Open Government Licence v3.0 (UK Government GHG Conversion Factors for Company Reporting 2026, DESNZ).

Greenhouse gas emission intensity of electricity generation in Europe (indicator ENER038) (European Environment Agency (EEA)) · ENER038, data 1990-2024, published 2026-07-10 · CC BY (version not stated) under the EEA legal notice (https://www.eea.europa.eu/en/legal-notice): re-use, including commercial, with the EEA acknowledged in each copy and the meaning not distortedSource: European Environment Agency (EEA), indicator ENER038 'Greenhouse gas emission intensity of electricity generation in Europe' (2026), https://www.eea.europa.eu/en/analysis/indicators/greenhouse-gas-emission-intensity-of-1, CC BY; values converted from g to kg CO2e per kWh.

ScenarioClimate change (kg CO2-eq)
baseline66.72
de-grid not comparable104.7
nl-grid not comparable88.29

Inventory per 1 t GOX (42 flows)

FlowPhaseDirectionQuantityUnitProvenance
Ambient airoperationinput3,813kggiven
Electric power (6.6 kV grid supply)operationinput352.1kWhassumed
GOX to pipelineoperationoutput1,000kgassumed
GAN to battery limitoperationoutput599.7kgassumed
LOX to storageoperationoutput22.53kgassumed
LIN to storageoperationoutput22.53kgassumed
Vent to atmosphereoperationoutput2,583kgassumed
Condensate (MAC cooler drains; DCAC condensate into its circulating water)operationoutput75.78kgcalculated
Cooling water return (heat rejected)operationoutput360.7kWhcalculated
AR to the environmentoperationoutput45.18kgassumed
CO2 to the environmentoperationoutput2.382kgassumed
H2O to the environmentoperationoutput80.56kgassumed
N2 to the environmentoperationoutput2,382kgassumed
O2 to the environmentoperationoutput148.6kgassumed
Structural steelconstructioninput0.09662kgcalculated
Pipeconstructioninput0.0008292mcalculated
Concreteconstructioninput0.00003088m3calculated
Gratingconstructioninput0.00009957m2calculated
Pipe insulationconstructioninput0.00005115m2calculated
Valvesconstructioninput0.00001826eacalculated
Flangesconstructioninput0.00006296eacalculated
Gasketsconstructioninput0.00006296eacalculated
Elbowsconstructioninput0.0001277eacalculated
Teesconstructioninput0.00001186eacalculated
Reducersconstructioninput0.0000001602eacalculated
In-line itemsconstructioninput0.000001122eacalculated
Aluminium equipmentconstructioninput0.02035kgassumed
Carbon steel equipmentconstructioninput0.07298kgassumed
Stainless steel equipmentconstructioninput0.0157kgassumed
Molecular sieve 13X and activated alumina (V-2101A/B)operationinput0.02403kgassumed
Lubricating oil (K-1101, K-4101, K-4102, K-3101)operationinput0.008011kgassumed
Maintenance: Structural steelmaintenanceinput0.02416kgcalculated
Maintenance: Pipemaintenanceinput0.0002073mcalculated
Maintenance: Pipe insulationmaintenanceinput0.00001279m2calculated
Maintenance: Valvesmaintenanceinput0.000004566eacalculated
Maintenance: Aluminium equipmentmaintenanceinput0.005087kgassumed
Maintenance: Carbon steel equipmentmaintenanceinput0.01824kgassumed
Maintenance: Stainless steel equipmentmaintenanceinput0.003925kgassumed
Transport (500 km)constructioninput0.1028tkmassumed
Transport (800 km)transportinput0.06676tkmassumed
End of life: steel-recyclingend-of-lifeoutput0.2085kgassumed
End of life: aluminium-recyclingend-of-lifeoutput0.02289kgassumed

Computed by ChemE-as-Code from lca/dataset.yaml, lca/factors.yaml, lca/gaps.csv, lca/inventory.csv, lca/lca.yaml, lca/mappings.yaml, lca/results.csv, lca/results.md, lca/uncertainty.csv.

Design cases and regional scenarios (3)

Technology

cryogenic double-column air separation, 500 t/d GOX, pumped liquid products, TSA front end

Design case

500 t/d GOX (14,600 Nm3/h) and 10,000 Nm3/h GAN; LOX and LIN 600 kg/h each

Design case: the D-099 design air (30 C, 80 % RH, 1.013 bara, 85,840 Nm3/h dry; design specification), ~83 % O2 recovery (D-066, ASSUMED) · capacity from process.yaml basis.capacity · the only computed design case; other capacities are not implemented

Background applicability: No region stated, 2026. Not a plant location.

No background region stated: no country highlighted. Not a plant location. Dashed amber: a background from GB stands in (proxy).
  • Calculation maturity Balanced
  • Inventory evidencePartial: data gaps2 linked · 11 proxy · 17 missing · 6 no burden · 2 released
  • Independent review Not independently reviewed

Characterised impact per 1 t GOXP, exergy allocation

66.7kg CO2-eqpartial: excludes data gaps

Proxy background: Electric power (6.6 kV grid supply) (GB) stands in. Read the number as screening, not as a regional footprint.

Basis: per 1 t GOXP · exergy allocation · boundary: cradle-to-gate.

Shares: GANP 23.9 % · GOXP 70.2 % · LIN 2.89 % · LOX 3.07 %. The per-unit value is allocated; the inventories below are for the whole plant and unallocated.

  • 18 exchanges without a burden in some category
  • factors ESTIMATE, PROXY
  • climate categories only: a carbon footprint, not a multi-impact LCA

Background-linked inventory per 1 h of operation

ExchangeAmountStateBackgroundRegionYear
Electric power (6.6 kV grid supply)UK grid at the consumer (incl. T&D, WTT) for a site whose country is not decided (D-092)10,465 kWhProxydesnz-ghg-2026:electricity-gbGB2026
Cooling water return (heat rejected)10,721 kWhLinkedcooling-waterGB2026
Molecular sieve 13X and activated alumina (V-2101A/B)no open factor for 13X molecular sieve or activated alumina production0.7143 kgMissing———
Lubricating oil (K-1101, K-4101, K-4102, K-3101)no open factor for lubricating oil production0.2381 kgMissing———
Construction, maintenance, transport and end of life (26, 15 missing)
ExchangeAmountStateBackgroundRegionYear
Structural steelUK construction metals (primary) for rack and structure steel2.872 kgProxydesnz-ghg-2026:metals-constructionGB2026
Pipeno open factor per m of pipe; the take-off gives length by DN, not mass0.02465 mMissing———
Concrete0.0009178 m3Linkedconcrete-m3GB2026
Gratingno open factor per m2 of grating0.002959 m2Missing———
Pipe insulationthe take-off gives m2; the open insulation factor is per t0.00152 m2Missing———
Valvesno open factor per piece0.0005429 eaMissing———
Flangesno open factor per piece0.001871 eaMissing———
Gasketsno open factor per piece0.001871 eaMissing———
Elbowsno open factor per piece0.003795 eaMissing———
Teesno open factor per piece0.0003524 eaMissing———
Reducersno open factor per piece0.000004762 eaMissing———
In-line itemsno open factor per piece0.00003333 eaMissing———
Aluminium equipmentUK primary aluminium of cans and foil (excl. forming) for brazed exchanger aluminium0.6048 kgProxydesnz-ghg-2026:aluminium-cans-foilGB2026
Carbon steel equipmentUK construction metals (primary) for carbon steel shells and casings2.169 kgProxydesnz-ghg-2026:metals-constructionGB2026
Stainless steel equipmentUK construction metals (primary) for stainless steel: likely an underestimate (alloying elements)0.4667 kgProxydesnz-ghg-2026:metals-constructionGB2026
Maintenance: Structural steelUK construction metals (primary) for rack and structure steel0.718 kgProxydesnz-ghg-2026:metals-constructionGB2026
Maintenance: Pipeno open factor per m of pipe; the take-off gives length by DN, not mass0.006162 mMissing———
Maintenance: Pipe insulationthe take-off gives m2; the open insulation factor is per t0.0003801 m2Missing———
Maintenance: Valvesno open factor per piece0.0001357 eaMissing———
Maintenance: Aluminium equipmentUK primary aluminium of cans and foil (excl. forming) for brazed exchanger aluminium0.1512 kgProxydesnz-ghg-2026:aluminium-cans-foilGB2026
Maintenance: Carbon steel equipmentUK construction metals (primary) for carbon steel shells and casings0.5423 kgProxydesnz-ghg-2026:metals-constructionGB2026
Maintenance: Stainless steel equipmentUK construction metals (primary) for stainless steel: likely an underestimate (alloying elements)0.1167 kgProxydesnz-ghg-2026:metals-constructionGB2026
Transport (500 km)UK average non-refrigerated HGV, average laden, incl. WTT3.056 tkmProxydesnz-ghg-2026:lorry-hgv-gbGB2026
Transport (800 km)UK average non-refrigerated HGV, average laden, incl. WTT1.984 tkmProxydesnz-ghg-2026:lorry-hgv-gbGB2026
End of life: steel-recyclingno open recycling credit: the DESNZ material factors are not suitable for recycling benefits (methodology 12.1)6.196 kgMissing———
End of life: aluminium-recyclingno open recycling credit: the DESNZ material factors are not suitable for recycling benefits (methodology 12.1)0.6804 kgMissing———
  • 1 equipment items have no dimensions.weight: gaps of their construction entry, not counted as 0: E-3103
  • consumable molecular-sieve is replaced or charged, but has no disposal: what goes in does not come out
  • emission sources the flowsheet does not carry, with neither an estimate nor a declared exclusion: V-3101 (a Tank: storage-tank), T-4101 (a Tank: storage-tank), T-4102 (a Tank: storage-tank)
  • product GOXP (GOX to pipeline) has no category: the TEA and LCA cannot tell a product from wastewater, off-gas, solid waste or an emission
  • product GANP (GAN to battery limit) has no category: the TEA and LCA cannot tell a product from wastewater, off-gas, solid waste or an emission
  • product LOX (LOX to storage) has no category: the TEA and LCA cannot tell a product from wastewater, off-gas, solid waste or an emission
  • product LIN (LIN to storage) has no category: the TEA and LCA cannot tell a product from wastewater, off-gas, solid waste or an emission
  • product VENT (Vent to atmosphere) has no category: the TEA and LCA cannot tell a product from wastewater, off-gas, solid waste or an emission
  • product COND (Condensate (MAC cooler drains; DCAC condensate into its circulating water)) has no category: the TEA and LCA cannot tell a product from wastewater, off-gas, solid waste or an emission
  • product CW (Cooling water return (heat rejected)) has no category: the TEA and LCA cannot tell a product from wastewater, off-gas, solid waste or an emission
  • step C1101U (Cooling) exchanges heat or work but no energy stream connects it to a utility: its steam, cooling, refrigeration or power is in no inventory
  • step C1102 (Cooling) exchanges heat or work but no energy stream connects it to a utility: its steam, cooling, refrigeration or power is in no inventory
  • step K3101 (Compressing) exchanges heat or work but no energy stream connects it to a utility: its steam, cooling, refrigeration or power is in no inventory
  • step E3105 (Cooling) exchanges heat or work but no energy stream connects it to a utility: its steam, cooling, refrigeration or power is in no inventory
  • step C3101 (Distilling) exchanges heat or work but no energy stream connects it to a utility: its steam, cooling, refrigeration or power is in no inventory
  • step HL3101 (ExchangingThermalEnergy) exchanges heat or work but no energy stream connects it to a utility: its steam, cooling, refrigeration or power is in no inventory
  • step C3102 (Distilling) exchanges heat or work but no energy stream connects it to a utility: its steam, cooling, refrigeration or power is in no inventory
Foreground inventory design case design, per 1 h of operation, unallocated (42 exchanges)
ExchangeTypeAmountUnitProvenance
Ambient airinput113,335kggiven
Electric power (6.6 kV grid supply)input10,465kWhassumed
GOX to pipelineproduct20,860kgassumed
GAN to battery limitproduct12,510kgassumed
LOX to storageproduct470kgassumed
LIN to storageproduct470kgassumed
Vent to atmosphereoutput76,773kgassumed
Condensate (MAC cooler drains; DCAC condensate into its circulating water)output2,252kgcalculated
Cooling water return (heat rejected)output10,721kWhcalculated
AR to the environmentemission1,343kgassumed
CO2 to the environmentemission70.79kgassumed
H2O to the environmentemission2,394kgassumed
N2 to the environmentemission70,799kgassumed
O2 to the environmentemission4,418kgassumed
Structural steelinput2.872kgcalculated
Pipeinput0.02465mcalculated
Concreteinput0.0009178m3calculated
Gratinginput0.002959m2calculated
Pipe insulationinput0.00152m2calculated
Valvesinput0.0005429eacalculated
Flangesinput0.001871eacalculated
Gasketsinput0.001871eacalculated
Elbowsinput0.003795eacalculated
Teesinput0.0003524eacalculated
Reducersinput0.000004762eacalculated
In-line itemsinput0.00003333eacalculated
Aluminium equipmentinput0.6048kgassumed
Carbon steel equipmentinput2.169kgassumed
Stainless steel equipmentinput0.4667kgassumed
Molecular sieve 13X and activated alumina (V-2101A/B)input0.7143kgassumed
Lubricating oil (K-1101, K-4101, K-4102, K-3101)input0.2381kgassumed
Maintenance: Structural steelinput0.718kgcalculated
Maintenance: Pipeinput0.006162mcalculated
Maintenance: Pipe insulationinput0.0003801m2calculated
Maintenance: Valvesinput0.0001357eacalculated
Maintenance: Aluminium equipmentinput0.1512kgassumed
Maintenance: Carbon steel equipmentinput0.5423kgassumed
Maintenance: Stainless steel equipmentinput0.1167kgassumed
Transport (500 km)input3.056tkmassumed
Transport (800 km)input1.984tkmassumed
End of life: steel-recyclingoutput6.196kgassumed
End of life: aluminium-recyclingoutput0.6804kgassumed

Foreground fingerprint 8cbb126bf7a1; the same for every background of this case.

Scenario asu-1-500-t-d-gox/design/baseline · machine-readable record

In the open LCI database (cheme-as-code-atlas-preview-c3ab348) as Oxygen, gaseous, >= 99.5 mol%, 30 barg; Nitrogen, gaseous, <= 10 ppm O2, 8 barg; Oxygen, liquid; Nitrogen, liquid.

Download it for Brightway, openLCA and other tools.

In the LCI database: system model, datasets and KPIs against the benchmarks

In the LCI database

System model
attributional, cut-off (methodology 1.1.0) · 2 exchanges left out under it
Allocation
exergy (physical-exergy, from mappings) · product:GANP 23.9 %, product:GOXP 70.2 %, product:LIN 2.9 %, product:LOX 3.1 %
Allocation findings
none
Change report
Not available: this build has no change report against an earlier release.
Dataset pages
Nitrogen, gaseous, <= 10 ppm O2, 8 barg · Oxygen, gaseous, >= 99.5 mol%, 30 barg · Nitrogen, liquid · Oxygen, liquid

KPI benchmark positions

KPIValueReference rangePosition
Cooling-water duty (heat rejected) per t of gaseous oxygen product
No open source found that states the cooling-water duty of a cryogenic air separation unit per t of oxygen product with its conditions: a web search of EU BREFs, IEA reports, open-access peer-reviewed papers and manufacturer literature on 2026-10-25 found compressor powers but no heat-rejection range. Most of the heat rejected is the compressors' shaft work (an energy balance, not a benchmark), so the KPI is reported without a range until a source is found. A second web search on 2026-10-30 (cooling-water consumption or heat rejection per t O2 of cryogenic ASUs) found none either.
– GJ/tnot availablenot evaluated
Oxygen recovery (O2 in the products per O2 in the air feed)– %97.85 to 97.85 %
Pfaff, I., Kather, A. (2009) Comparative thermodynamic analysis and integration issues of CCS steam power plants based on oxy-combustion with cryogenic or membrane based air separation. Energy Procedia 1:495-502, doi:10.1016/j.egypro.2009.01.066 (peer-reviewed)
not evaluated
Specific electric power per t of gaseous oxygen product– kWh/t400 to 600 kWh/t
Air Liquide Engineering & Construction (2017) Standard Plants: fully-packaged modular solutions, brochure, September 2017 (Yango standard air separation unit, specifications) (manufacturer)
not evaluated

Maturity and review

Design maturity Screening (claimed): Balances and estimates good enough to compare options. The deliverables of basic engineering exist (P&IDs, lists, datasheets, layout, estimate, LCA, HAZOP draft) and the engineering gates of stage basic pass (ChemE-as-Code checks). The calculation evidence reaches balanced, which supports screening (cheme maturity, checks/maturity.json): the air feed is the owner's design specification (D-099), the balances close, and the whole plant but the evaporative cooler is simulated in DWSIM. Predictive is not reached: the evaporative cooler is not simulated, the TSA is a specified component split, the plant energy closure is unsupported (D-097), and the property regime fails in cheme 1.2.1 (feed and streams outside the property package's benchmarked claim, D-117). Design reviews are recorded in reviews/; no independent engineering review has been made.

Calculation maturity, from the checked evidenceBalancedsupports the design maturity Screening

The checked evidence supports the level Balanced: A balanced conceptual flowsheet: the process rules pass, every mass and component balance closes within its tolerance, and every reactor and separator rests on sourced data.

The four levels: 2 of 4 achieved (Sourced ✓, Balanced ✓, Predictive ✕, Engineering ✕)

  1. Sourced

    Achieved

    A sourced process description: the flowsheet and design basis are valid, and every feed is given with a source.

    Every required criterion of this level and of the levels below passes. What Sourced requires

    Criteria and evidence (3 of 3 pass)

  2. Balanced

    Achieved

    A balanced conceptual flowsheet: the process rules pass, every mass and component balance closes within its tolerance, and every reactor and separator rests on sourced data.

    Every required criterion of this level and of the levels below passes. What Balanced requires

    Criteria and evidence (4 of 5 pass)
    • Passno error in the process rules (units, ports, reactions, reactors)

      process/flowsheet.yaml · cheme.maturity-balanced-process-rules

    • Passevery block and step balance evaluable in every case (mass and components or elements)

      process/flowsheet.yaml · cheme.maturity-balanced-balances-evaluable

    • Passevery balance closes within the flowsheet's explicit tolerance

      process/flowsheet.yaml · cheme.maturity-balanced-balances-closed

    • Passevery reactor and separator rests on a sourced model or sourced specified values

      process/flowsheet.yaml · cheme.maturity-balanced-model-basis

    • Failenergy balances of the blocks and steps (stream enthalpies against energy streams) (reported, not required)

      imbalance: PRD (design), K4101 (design), K4102 (design)

      To resolve: check the duties and the calculated enthalpies of those nodes

      process/flowsheet.yaml · cheme.maturity-balanced-energy-closure

  3. Predictive

    Not yet achieved

    A converged predictive simulation, current with its inputs, with every reactor and separator predicted by a model, the property methods inside their benchmarked ranges and the energy balance closed.

    3 required criteria fail or are missing: every step simulated: none excluded and left at specified values, every reactor and separator predicted by a model: specified splits, conversions and stream values cap the level at balanced, the property methods are used inside their declared regimes. 1 more cannot be checked yet. What Predictive requires

    Criteria and evidence (10 of 14 pass)
    • Passprocess/simulation.yaml translates into a simulator model for every case

      process/simulation.yaml · cheme.maturity-predictive-simulation-spec

    • Passa run record for every case

      process/simulation-run.json · cheme.maturity-predictive-run-record

    • Passevery run record is current: simulated from the inputs as they are (fingerprints)

      process/simulation-run.json · cheme.maturity-predictive-current

    • Passevery recorded run converged without errors

      process/simulation-run.json · cheme.maturity-predictive-converged

    • Passsimulator, simulator version, property package and core version recorded

      process/simulation-run.json · cheme.maturity-predictive-solver

    • Failevery step simulated: none excluded and left at specified values

      excluded: C1102

      To resolve: their streams stay specified; simulate them to claim predictive

      process/simulation.yaml · cheme.maturity-predictive-coverage

    • Passphysical validity: the balances of the simulated flowsheet close within tolerance

      process/flowsheet.yaml · cheme.maturity-predictive-balances

    • Failevery reactor and separator predicted by a model: specified splits, conversions and stream values cap the level at balanced

      specified: V2101 (component-split)

      To resolve: replace specified splits and conversions by predictive unit models

      process/simulation.yaml · cheme.maturity-predictive-model-basis

    • Passthe property package is supported and recommended by a recorded method selection (or a recorded substitution)

      process/simulation.yaml · cheme.maturity-predictive-property-package

    • Failthe property methods are used inside their declared regimes

      simulation.yaml sets interaction parameters (AR-O2); the claim holds for DWSIM's own, case design, feed S1: component 124-38-9 is not in the claim, case design, feed S1: component 7732-18-5 is not in the claim and 23 more

      To resolve: keep every feed and stream inside the claimed boxes of the package (thermodynamics/methods.yml, benchmarked by tests/test_process_simulate_property_package.py), or extend the benchmark

      process/simulation.yaml · cheme.maturity-predictive-property-regime

    • Passevery stream with calculated properties lies inside the benchmarked claim of the process's property package

      process/flowsheet.yaml · cheme.maturity-predictive-stream-properties

    • Unsupportedthe simulated plant's enthalpy flows close with its heat and work within tolerance

      the plant closure is not evaluated (case design: unsupported: V2101: the sign of the component separator's energy imbalance is not established; C3102: the sign of the column top's residual duty is not established): a reacting unit without a heat-of-formation basis (its property package's enthalpy reference is not verified, or the run did not report DWSIM's formation enthalpies), or a unit whose duty sign is not established, so energy conservation cannot be shown

      To resolve: satisfied once every unit's closure is evaluable: reactors on a verified package (simulation/energy.py FORMATION_PACKAGES) in a current run; no component separator or column top without condenser

      process/simulation-run.json · cheme.maturity-predictive-energy-closure

    • Passno exchanger temperature cross or approach below its minimum, every utility level can serve its duty

      process/simulation-run.json · cheme.maturity-predictive-exchangers

    • Passthe simulated reaction heat agrees with the formation enthalpies declared in process/materials.yaml

      no reacting unit in the simulated plant

      process/simulation-run.json · cheme.maturity-predictive-formation-data

  4. Engineering

    Not yet achieved

    A preliminary/basic engineering package (equipment list, datasheets, P&IDs, process links) on top of the levels below. Not detailed engineering, and not a review.

    Its own criteria pass, but Predictive is not established, and a level needs every level below it. What Engineering requires

    Criteria and evidence (4 of 5 pass)
    • Passan equipment list

      equipment/equipment-list.yaml · cheme.maturity-engineering-equipment-list

    • Passa valid, final datasheet for every equipment item

      equipment/datasheets/ · cheme.maturity-engineering-datasheets

    • PassP&IDs without errors

      pid/ · cheme.maturity-engineering-pid

    • Passevery flowsheet link resolves against the lists and the sheets

      process/flowsheet.yaml · cheme.maturity-engineering-process-links

    • Unsupporteddatasheet duties and sizes cross-checked against the current simulation (reported, not required)

      not cross-checked by this command

      equipment/datasheets/ · cheme.maturity-engineering-consistency

Artifact completeness

Which deliverables exist. They never raise a calculation maturity level: a drawing from unchecked numbers is still unchecked.

  • Drawings: 6 of 6 declared sheets drawn
  • Design basis: present
  • Equipment list: present
  • Datasheets: 40 files
  • Line list: present
  • Instrument list: present
  • Layout: 7 files
  • Cost estimate: 3 files
  • LCA files: 5 files
  • Simulation run record: present

Independent review

Not independently reviewed

No independent engineering review yet. Automated checks passing is not a review.

Set by people only. Reaching a calculation maturity level or passing automated checks is not an independent review or an approval.

Assumptions, limitations and checked cases
Operating caseBalances closeSimulated
design (default)
Design case: the D-099 design air (30 C, 80 % RH, 1.013 bara, 85,840 Nm3/h dry; design specification), ~83 % O2 recovery (D-066, ASSUMED)
yesyes

The levels hold for these cases only; the criteria name the property and model ranges they were checked against.

Design basis assumptions (7)
  • ASSUMED O2 recovery ~83 % (D-066: no argon column, 99.5 % purity, GAN drawn from the HP column (13 % of the HP column air), 13 % Lachmann air; was 94 %, which the simulated double column does not reach).
  • ASSUMED MAC discharge 5.8 bara, HP column top 5.4 bara, LP column top 1.3 bara.
  • ASSUMED refrigeration by booster-braked expander, Lachmann air to the LP column, ~11,500 Nm3/h, ~198 kW (D-061); the boosted air enters the main exchanger at 15 C (D-067).
  • ASSUMED regeneration gas ~14,600 Nm3/h waste N2 (D-066), heated electrically to 200 C.
  • ASSUMED DCAC air outlet 12 C via chilled water from an N2 evaporative cooler; no mechanical chiller. All waste N2 not used for regeneration goes to the evaporative cooler; its chilled water also trims the booster air to 15 C (D-067).
  • ASSUMED GAN taken as pressurized N2 from the HP column top (~5.2 bara) and compressed to 9 bara.
  • ASSUMED all flows, pressures, duties and DNs are concept estimates, accuracy about +/-30 %.
Values marked as assumed (117)
  • process/flowsheet.yaml: 68
  • process/simulation.yaml: 49
Limitations (26)
  • V2101: specified split: the separation is not predicted
  • predictive.energy-closure: the plant closure is not evaluated (case design: unsupported: V2101: the sign of the component separator's energy imbalance is not established; C3102: the sign of the column top's residual duty is not established): a reacting unit without a heat-of-formation basis (its property package's enthalpy reference is not verified, or the run did not report DWSIM's formation enthalpies), or a unit whose duty sign is not established, so energy conservation cannot be shown
  • engineering.consistency: not cross-checked by this command
  • engineering: mechanical design to a code (wall thickness, nozzle loads) is not checked
  • engineering: materials and corrosion selection is not checked
  • engineering: relief and blowdown sizing is not checked
  • engineering: control and dynamic behaviour is not checked
  • predictive.property-package: substituted property package: property package 'Peng-Robinson (PR)' is a substitution for Peng-Robinson with Wong-Sandler mixing rules (loses: the Wong-Sandler (excess Gibbs energy) mixing rules; classical one-fluid mixing with kij); accepted: Peng-Robinson for an air separation unit: the cryogenic part (N2, O2, Ar, where the column and exchanger results matter) is non-polar, and the polar water is only in the warm end, at most 3.4 mol%, removed as near-pure condensate and in the TSA. Known limitation: PR gives water at saturation 10-13 % low (D-058); the adsorbers are sized on the IAPWS-95 water load (D-080). Proposed by the agent in D-097. Accepted (D-103) by the agent on the owner's delegation of 2026-10-25, not as the owner's own judgement: PR with the D-066 Ar/O2 kij is suitable for N2/O2/Ar vapour-liquid equilibrium at these conditions (1.3-5.5 bara, 80-100 K), and water appears only at the warm end and in the condensates, where the duties are small. The limitation stays listed.
  • simulation-route: no electrolytes: the worker exposes no electrolyte property package
  • simulation-route: no pseudocomponents: every compound must be in DWSIM's database (by CAS number or the name in simulation.yaml); no assay characterisation
  • simulation-route: no solid phase: simulation.yaml has no solid compounds or solid-phase input, and none is tested
  • simulation-route: binary interaction parameters: DWSIM's own database (not inspected by cheme-as-code) unless simulation.yaml interaction_parameters set them (equation-of-state packages only)
  • boundary: product GOXP (GOX to pipeline) has no category: the TEA and LCA cannot tell a product from wastewater, off-gas, solid waste or an emission
  • boundary: product GANP (GAN to battery limit) has no category: the TEA and LCA cannot tell a product from wastewater, off-gas, solid waste or an emission
  • boundary: product LOX (LOX to storage) has no category: the TEA and LCA cannot tell a product from wastewater, off-gas, solid waste or an emission
  • boundary: product LIN (LIN to storage) has no category: the TEA and LCA cannot tell a product from wastewater, off-gas, solid waste or an emission
  • boundary: product VENT (Vent to atmosphere) has no category: the TEA and LCA cannot tell a product from wastewater, off-gas, solid waste or an emission
  • boundary: product COND (Condensate (MAC cooler drains; DCAC condensate into its circulating water)) has no category: the TEA and LCA cannot tell a product from wastewater, off-gas, solid waste or an emission
  • boundary: product CW (Cooling water return (heat rejected)) has no category: the TEA and LCA cannot tell a product from wastewater, off-gas, solid waste or an emission
  • boundary: step C1101U (Cooling) exchanges heat or work but no energy stream connects it to a utility: its steam, cooling, refrigeration or power is in no inventory
  • boundary: step C1102 (Cooling) exchanges heat or work but no energy stream connects it to a utility: its steam, cooling, refrigeration or power is in no inventory
  • boundary: step K3101 (Compressing) exchanges heat or work but no energy stream connects it to a utility: its steam, cooling, refrigeration or power is in no inventory
  • boundary: step E3105 (Cooling) exchanges heat or work but no energy stream connects it to a utility: its steam, cooling, refrigeration or power is in no inventory
  • boundary: step C3101 (Distilling) exchanges heat or work but no energy stream connects it to a utility: its steam, cooling, refrigeration or power is in no inventory
  • boundary: step HL3101 (ExchangingThermalEnergy) exchanges heat or work but no energy stream connects it to a utility: its steam, cooling, refrigeration or power is in no inventory
  • boundary: step C3102 (Distilling) exchanges heat or work but no energy stream connects it to a utility: its steam, cooling, refrigeration or power is in no inventory
Where the evidence comes from
Report
Maturity report (JSON) · checks/maturity.json in the repository (the parts that may be published)
Checked
2026-11-01 05:34 UTC
ChemE-as-Code
1.2.1
Inputs at
fa2c2d3
Input fingerprints
7 files

"Outdated" compares these files only: core does not fingerprint drawings, datasheets and the other engineering files.

  • equipment/equipment-list.yaml 7dd6ae258db6
  • plant.yaml 29c11e86f63f
  • process/design-basis.yaml 0498974de4c6
  • process/flowsheet.yaml 55cd2ae5678e
  • process/materials.yaml e1aa43b3af06
  • process/simulation-run.json 3e227e41149c
  • process/simulation.yaml 74863bd0654b
Design basis
process/design-basis.yaml
Method
How ChemE-as-Code checks the levels (requirement by requirement)

Open items

12 open items · 6 closed

Before gateAction itemEngineering holdTechnical query (TQ)Design changeOpen
Detail engineering731112

Before the detail engineering gate

New action itemNew engineering holdNew technical queryNew design changeAll issues

Sources

Engineering project
ASU-1 (500 t/d GOX) · cheme-as-code>=0.8
Library version
c3ab348 (process last changed in c3ab348)
Drawings rendered by
cheme 1.6.0 (pyDEXPI 2.1.0)
Data
Catalog record (JSON) · CC-BY-4.0
Files
View the files on GitHub · change history and authors

References

How to cite

For the data, cite the Process Atlas paper; for the platform that builds and checks it, the ChemE-as-Code paper.

Schweidtmann, A. M. & Weber, J. M. (2026, in preparation). Process Atlas: an open, git-native, reproducible library and life cycle inventory of chemical processes (working title).

For this process: "Cryogenic air separation unit (500 t/d GOX)", ChemE-as-Code process library, version c3ab348.

BibTeX
@unpublished{schweidtmann_process_atlas,
  author = {Schweidtmann, Artur M. and Weber, Jana M.},
  title = {{Process Atlas: an open, git-native, reproducible library and life cycle inventory of chemical processes (working title)}},
  year = {2026},
  url = {https://atlas.cheme-as-code.org},
  note = {in preparation}
}

Schweidtmann, A. M. (2026, in preparation). ChemE-as-Code: An Open-Source Platform for AI-Accelerated Chemical Process Engineering (working title).

BibTeX
@unpublished{schweidtmann_cheme_as_code,
  author = {Schweidtmann, Artur M.},
  title = {{ChemE-as-Code: An Open-Source Platform for AI-Accelerated Chemical Process Engineering (working title)}},
  year = {2026},
  url = {https://cheme-as-code.org},
  note = {in preparation}
}