Hydrogen Production with NeqSim

NeqSim covers thermochemical and electrochemical hydrogen production routes natively:

  1. Grey / blue H₂ — steam methane reforming (SMR), autothermal reforming (ATR), or partial oxidation (POX), followed by optional water-gas shift, pressure-swing adsorption (PSA) purification, and downstream CO₂ capture.
  2. Green / pink H₂ — water electrolysis using PEM, alkaline, SOEC, or AEM stacks.

This page documents the hydrogen-production route models, PSA cascade and PSA CAPEX additions, electrolysis stack models, and foundation utilities for cryogenic H₂ spin-isomer corrections and catalyst life screening. Companion guides: CO₂ injection well analysis and reaction engineering reformer kinetics.

Applicable standards

Standard Scope
ISO 14687 Hydrogen fuel quality (PEM-FC grade ≥ 99.97% H₂)
ISO 22734 Industrial water electrolyzers — safety
IEC 62282 Fuel cell technologies (electrochemistry conventions)
API 941 Steels for H₂ service (Nelson curves)
ASME B31.12 Hydrogen piping and pipelines
EIGA Doc 121 H₂ generator design (SMR / electrolysis)
IRENA 2022 Green H₂ cost benchmarks
IEA Global H₂ Review 2023 Capacity factors, USD/kW benchmarks

Core classes

Class Package Purpose
CatalyticTubeReformer neqsim.process.equipment.reactor Tube-side SMR equilibrium model with duty, pressure-drop, tube-wall, heat-flux, and catalyst activity screening
ReformerFurnace neqsim.process.equipment.reactor Fired SMR furnace coupling combustion heat from FurnaceBurner to catalytic tube reformer duty
SyngasBurnerZone neqsim.process.equipment.reactor Oxygen-blown ATR/POX burner-zone model with O₂/C envelope and flame-temperature screening
AutothermalReformer neqsim.process.equipment.reactor ATR template with O₂/C and S/C controls, burner zone, catalytic equilibrium zone, and soot-risk metric
PartialOxidationReactor neqsim.process.equipment.reactor POX template with O₂/C control, refractory-temperature warning, fast-quench section, and H₂/CO metric
QuenchSection neqsim.process.equipment.reactor Rapid syngas cooling model with heat removed and quench severity outputs
WaterGasShiftReactor neqsim.process.equipment.reactor HT/LT WGS equilibrium wrapper with CO conversion, H2 gain, CO2 formation, duty, and WGS ratio reporting
ComponentCaptureUnit neqsim.process.equipment.splitter Selective component capture placeholder for CO2 capture, H2 drying, and other screening separations
PressureSwingAdsorptionBed neqsim.process.equipment.adsorber H₂-tuned single PSA bed (AC or Zeolite 13X)
PSACascade neqsim.process.equipment.adsorber Multi-bed Skarstrom cascade with pressure-equalisation recovery uplift
Electrolyzer neqsim.process.equipment.electrolyzer Stack model with technology defaults and Faradaic efficiency
ElectrolyzerTechnology neqsim.process.equipment.electrolyzer Enum PEM / ALKALINE / SOEC / AEM with default V, j, T, P, η_F
ElectrolyzerIVCharacteristic neqsim.process.equipment.electrolyzer Tafel + ohmic voltage model
ElectrolyzerCostEstimate neqsim.process.costestimation.electrolyzer Specific-CAPEX × scale × CEPCI
PSACostEstimate neqsim.process.costestimation.adsorber PSA vessel + switching valve skid + sorbent inventory CAPEX
ParaOrthoH2Correction neqsim.thermo.util.hydrogen Equilibrium para fraction, conversion heat, Cp and thermal-conductivity correction factors
CatalystDeactivationKinetics neqsim.process.equipment.reactor Sulfur/chloride/coking/sintering activity decay for H₂-production catalysts
SMRHydrogenPlantBuilder neqsim.process.hydrogen Screening plant builder for methane/steam feed, fired reformer, and optional PSA
ATRHydrogenPlantBuilder neqsim.process.hydrogen Screening plant builder for methane/steam/oxygen feed, ATR, and optional PSA
POXHydrogenPlantBuilder neqsim.process.hydrogen Screening plant builder for POX syngas or hydrogen route studies with optional PSA
BlueHydrogenPlantBuilder neqsim.process.hydrogen Full screening chain for SMR + HT/LT WGS + CO2 capture/compression + PSA + H2 drying/compression + carbon intensity

Thermochemical reformer route templates

The thermochemical route models are screening-grade process equipment: they use NeqSim equilibrium reactors and local engineering metrics to make route studies repeatable before users add detailed WGS, heat recovery, burner layout, amine capture, or vendor reactor design data.

Technology NeqSim pattern Maturity Remaining high-fidelity scope
Steam methane reforming (SMR) ReformerFurnace + CatalyticTubeReformer + FurnaceBurner 4/5 Detailed radiant-box view factors, burner CFD, tube metallurgy/vendor rating
Autothermal reforming (ATR) AutothermalReformer with SyngasBurnerZone + catalytic GibbsReactor 4/5 Burner aerodynamics, oxygen-mixing CFD, rate-based catalyst bed calibration
Partial oxidation (POX) PartialOxidationReactor + SyngasBurnerZone + QuenchSection 3/5 Fast-quench kinetics, refractory thermal model, soot/coke kinetics

SMR fired reformer builder

ProcessSystem process = new SMRHydrogenPlantBuilder().setName("SMR screening")
  .setMethaneFeedMolePerSec(100.0)
  .setSteamToCarbonRatio(3.0)
  .setIncludePsa(true)
  .build();
process.run();

ReformerFurnace furnace =
  (ReformerFurnace) process.getUnit("SMR screening reformer furnace");
double tubeDutyKW = furnace.getTubeHeatDemandKW();
double heatBalance = furnace.getHeatBalanceRatio();
double methaneConversion = furnace.getTubeReformer().getMethaneConversion();

ReformerFurnace exposes stable syngas and flue-gas outlet streams, so downstream equipment such as WGS reactors, heat exchangers, PSA, or CO₂-capture units can be wired from getSyngasOutStream() and getFlueGasOutStream().

ATR and POX builders

ProcessSystem atrProcess = new ATRHydrogenPlantBuilder().setName("ATR screening")
  .setMethaneFeedMolePerSec(100.0)
  .setSteamToCarbonRatio(1.5)
  .setOxygenToCarbonRatio(0.60)
  .setIncludePsa(true)
  .build();
atrProcess.run();

AutothermalReformer atr =
  (AutothermalReformer) atrProcess.getUnit("ATR screening autothermal reformer");
double atrConversion = atr.getMethaneConversion();
double atrSootRisk = atr.getSootRiskIndex();

ProcessSystem poxProcess = new POXHydrogenPlantBuilder().setName("POX screening")
  .setMethaneFeedMolePerSec(100.0)
  .setOxygenToCarbonRatio(0.55)
  .setSteamToCarbonRatio(0.20)
  .build();

ATR and POX both rebuild the controlled inlet composition from the methane basis before running, so setOxygenToCarbonTarget() and setSteamToCarbonTarget() apply deterministically even when the starting stream has a different O₂/C or S/C ratio. toJson() on each unit returns the key route-screening metrics.

Blue H₂ — full process chain

BlueHydrogenPlantBuilder now creates a complete screening flowsheet for a blue-H2 front end. The default route is:

  1. methane/steam feed to fired SMR furnace
  2. high-temperature WGS and low-temperature WGS equilibrium stages
  3. shifted-gas cooler and condensate knock-out
  4. selective CO2 capture placeholder plus CO2 export compressor
  5. PSA cascade for H2 purification
  6. H2 dryer placeholder and H2 export compressor
  7. residual and gross carbon-intensity reporting
BlueHydrogenPlantBuilder builder = new BlueHydrogenPlantBuilder()
  .setName("Blue H2 screening")
  .setMethaneFeedMolePerSec(100.0)
  .setSteamToCarbonRatio(3.0)
  .setCo2CaptureFraction(0.90)
  .setCo2ExportPressure(110.0)
  .setH2ExportPressure(100.0)
  .setIncludePsa(true);

ProcessSystem process = builder.build();
process.run();

double h2KgPerHr = builder.getHydrogenProductMassFlowKgPerHour();
double capturedCo2KgPerHr = builder.getCapturedCo2MassFlowKgPerHour();
double residualIntensity = builder.getCarbonIntensityKgCO2PerKgH2();
double grossIntensity = builder.getGrossCarbonIntensityKgCO2PerKgH2();
String resultsJson = builder.toJson();

The CO2 capture and H2 dryer blocks use ComponentCaptureUnit: a deterministic component-removal placeholder that routes a selected component fraction to a captured stream and the remainder to a treated stream. Replace these with amine, membrane, or molecular-sieve models when project-specific design data are available.

WaterGasShiftReactor is also available as a standalone unit. It treats methane, nitrogen, and oxygen as inert while equilibrating CO, water, CO2, and H2. Key outputs are getCarbonMonoxideConversion(), getHydrogenMoleFlowGain(), getCarbonDioxideMoleFlowFormation(), getHeatDutyKW(), and getWgsEquilibriumRatio().

PSA purification

After SMR + HT/LT WGS + cooler + knock-out drum, the wet syngas is purified to fuel-cell grade in a PSA bed:

PressureSwingAdsorptionBed psa = new PressureSwingAdsorptionBed("PSA", koVap);
psa.setSorbent(PressureSwingAdsorptionBed.SorbentType.ACTIVATED_CARBON);
psa.setRecoveryTarget(0.88);   // typical 0.80–0.90
psa.run();

double purityH2  = psa.getH2Purity();              // > 0.999 for FC grade
double recovery  = psa.getH2Recovery();            // operating value
double[] tail    = psa.getTailGasComposition();    // for furnace LHV
double tailMoles = psa.getTailGasMoleFlow();       // mol/s for fuel-gas balance

Notes:

Multi-bed PSA cascade

Industrial H₂ PSA plants use multiple beds so adsorption, blowdown, purge, repressurisation, and pressure-equalisation steps can run continuously. The PSACascade class wraps one PressureSwingAdsorptionBed template and applies a cycle-averaged recovery uplift for the configured number of beds:

PSACascade psa = new PSACascade("H2 PSA", koVap);
psa.setConfiguration(PSACascade.CascadeConfiguration.BEDS_8);
psa.setSorbent(PressureSwingAdsorptionBed.SorbentType.ACTIVATED_CARBON);
psa.setPerBedRecoveryTarget(0.85);
psa.setCycleTime(300.0);
psa.setBedDiameter(2.0);
psa.setBedLength(4.0);
psa.run();

double purityH2 = psa.getH2Purity();
double recovery = psa.getH2Recovery();
Stream tailGas = psa.getTailGasStream();
Configuration Beds Pressure equalisation steps Recovery uplift
BEDS_2 2 0 0.00
BEDS_4 4 1 0.05
BEDS_6 6 2 0.08
BEDS_8 8 3 0.10
BEDS_10 10 4 0.11
BEDS_12 12 5 0.12

Cascade recovery is perBedRecoveryTarget + uplift, capped at 0.93. Purity is taken from the template bed because pressure equalisation mainly recovers H₂ that would otherwise leave with tail gas; it does not change sorbent selectivity.

Benchmark validation

Hydrogen route tests now include benchmark-style envelopes rather than only smoke tests. HydrogenProductionBenchmarkTest runs SMR, ATR, POX, and the full blue-H2 chain and checks that conversion, O2/C, H2/CO, PSA/capture behavior, H2 product rate, and carbon-intensity metrics remain in physically credible screening ranges. These tests are deliberately range-based so improved EOS or reactor solvers can move the answer without breaking validation, while large model regressions are still caught.

Green H₂ — water electrolysis

Set up a stream of liquid water and let the technology selector apply the voltage, current density, temperature, pressure, and Faradaic efficiency defaults:

Electrolyzer el = new Electrolyzer("PEM stack", waterFeed);
el.setTechnology(ElectrolyzerTechnology.PEM);
el.setIVCharacteristic(new ElectrolyzerIVCharacteristic(ElectrolyzerTechnology.PEM));
el.run();

double powerKW = el.getStackPower();
double sec     = el.getSpecificEnergyConsumption_kWh_per_kg_H2();
double Vcell   = el.getCellVoltage();   // recomputed from I-V at run time

Technology selector

Tech $V_{cell}$ (V) $j$ (A/cm²) $T$ (°C) $P$ (bara) $\eta_F$ SEC (kWh/kg H₂)
PEM 1.80 2.0 80 30 0.65 ~45–55
ALKALINE 1.85 0.4 80 7 0.62 ~50–60
SOEC 1.30 1.0 800 1 0.85 ~35–40 (HHV)
AEM 1.85 0.8 60 10 0.60 ~55–65

Sources: IRENA 2022 Hydrogen Decarbonisation Pathways; Buttler & Spliethoff, RSER 82 (2018); IEA Global Hydrogen Review 2023.

I-V model

\[V_{cell}(j, T) = E_{rev}(T) + A \cdot \log_{10}\!\left(\frac{j}{j_0}\right) + R \cdot j\]

with the Larminie & Dicks reversible voltage:

\[E_{rev}(T) = 1.229\;\text{V} + (-0.85\;\text{mV/K}) \cdot (T - 298.15\;\text{K})\]

Tafel slope $A$, exchange current density $j_0$, and area-specific resistance $R$ are technology-specific defaults inside ElectrolyzerIVCharacteristic. Below $j_0$ the model returns $E_{rev}$ (no spurious negative overpotential).

Electrolyzer CAPEX estimate

el.initMechanicalDesign();
ElectrolyzerMechanicalDesign mech =
    (ElectrolyzerMechanicalDesign) el.getMechanicalDesign();
mech.calcDesign();   // populates totalPowerKW

ElectrolyzerCostEstimate cost = new ElectrolyzerCostEstimate(mech);
cost.setTechnology("PEM");
double usd = cost.getPurchasedEquipmentCost();

Defaults (2024 USD/kW at CEPCI = 800): PEM 1250, Alkaline 800, SOEC 2500, AEM 1500. Scale exponent 0.85 vs reference 1 MW; setIncludeBalanceOfPlant(false) strips ~35% for stack-only quotes. AACE Class 4–5 — do not use for FID without vendor budget quotes.

PSA CAPEX estimate

PSACostEstimate estimates PSA skid purchased equipment cost from the bed count, per-bed vessel volume, switching valve skid, sorbent inventory, and CEPCI ratio. The constructor from PSACascade is the simplest path because it reads bed count, sorbent, diameter, and length directly from the cascade template bed:

PSACascade psa = new PSACascade("H2 PSA", koVap);
psa.setConfiguration(PSACascade.CascadeConfiguration.BEDS_8);
psa.setSorbent(PressureSwingAdsorptionBed.SorbentType.ZEOLITE_13X);
psa.setBedDiameter(2.2);
psa.setBedLength(5.0);

PSACostEstimate cost = new PSACostEstimate(psa);
double purchasedUsd = cost.getPurchasedEquipmentCost();

cost.setIncludeBalanceOfPlant(false);
double stackOnlyUsd = cost.getPurchasedEquipmentCost();

Cost basis: USD 250 000 reference vessel at 2 m diameter × 4 m tangent length, scale exponent 0.6, USD 60 000 switching-valve skid per bed, activated carbon at USD 4/kg, Zeolite 13X at USD 10/kg, and CEPCI 800 reference. This is an AACE Class 4–5 screening estimate.

Cryogenic H₂ spin-isomer corrections

Normal hydrogen is approximately 25% para and 75% ortho at ambient temperature. In liquid-hydrogen service the equilibrium mixture shifts strongly toward para-hydrogen, releasing conversion heat that must be removed in liquefaction and storage systems. ParaOrthoH2Correction provides a compact screening model:

double para20K = ParaOrthoH2Correction.getEquilibriumParaFraction(20.0);
double heatJPerKg = ParaOrthoH2Correction.getNormalToEquilibriumHeatJPerKg(20.0);
double cpCorrection = ParaOrthoH2Correction.getCpCorrectionJPerKgK(40.0);
double conductivityFactor = ParaOrthoH2Correction.getThermalConductivityCorrectionFactor(20.0);
double tauSeconds = ParaOrthoH2Correction.estimateEquilibrationTimeSeconds(
  77.0, ParaOrthoH2Correction.ConversionCatalyst.HYDROUS_FERRIC_OXIDE);

The partition-function model approaches 25% para at warm temperatures and >99% para near 20 K. The conversion heat is positive for exothermic conversion from normal hydrogen to the lower-energy equilibrium mixture. Thermal-conductivity factors are bounded screening multipliers for normal-H₂ correlations, not a replacement for detailed Leachman/NIST transport data.

Catalyst deactivation screening

Hydrogen-production catalysts can lose activity through sulfur poisoning, chloride poisoning, coking, and thermal sintering. CatalystDeactivationKinetics provides first-order screening rates for nickel SMR catalysts, iron-chromium HT-shift catalysts, copper-zinc LT-shift catalysts, and ruthenium ammonia-cracking catalysts:

CatalystBed bed = new CatalystBed();
CatalystDeactivationKinetics kinetics = new CatalystDeactivationKinetics(
  CatalystDeactivationKinetics.CatalystFamily.NICKEL_REFORMING)
    .setTemperature(973.15)
    .setSulfurPpmv(0.05)
    .setCarbonPotential(0.5)
    .setSteamToCarbonRatio(2.5)
    .setOperationHours(8000.0);

double activity = kinetics.applyTo(bed);
double timeTo80 = kinetics.estimateTimeToActivity(0.80);
String mechanism = kinetics.getDominantMechanism();

Use this as an early design or digital-twin input for activity-factor studies. Replace the default coefficients with vendor or plant-history data before using the result for guaranteed catalyst run length.

Color taxonomy

Color Route NeqSim primitives
Grey SMR, no CCS GibbsReactor + WGS + PressureSwingAdsorptionBed
Blue SMR/ATR + CCS Add CO₂ capture and compression downstream — see CO₂ injection well analysis
Green Renewable electrolysis Electrolyzer (PEM / Alkaline) + renewable power
Pink Nuclear electrolysis Same Electrolyzer, accounting differs
Turquoise Methane pyrolysis Horizon 2 — not yet implemented

Common pitfalls

Tests

Test class Coverage
PressureSwingAdsorptionBedTest Defaults, recovery cap, mass balance, composition, sorbent switch
ElectrolyzerTechnologyTest Per-tech default consistency
ElectrolyzerIVCharacteristicTest $E_{rev}$ vs $T$, Tafel monotonicity, technology ordering
ElectrolyzerTest Backward compat + $\eta_F$ + I-V + specific-energy band
ElectrolyzerCostEstimateTest Per-tech ordering, BoP toggle, scale economy
PSACascadeTest Bed-count uplift, 0.93 recovery cap, tail-gas balance, invalid inputs
PSACostEstimateTest Bed-count cost scaling, sorbent cost ordering, BoP toggle, cascade constructor
ParaOrthoH2CorrectionTest Equilibrium para fraction, conversion heat, Cp correction, conductivity factor, catalyst time ranking
CatalystDeactivationKineticsTest Catalyst-family sensitivity, coking, sintering, dominant mechanism, CatalystBed activity update
HydrogenProductionReactorTest SMR tube/furnace metrics, WGS metrics, ATR ratio controls, POX quench/refractory metrics, equipment factory aliases
ComponentCaptureUnitTest Selective component capture, actual removal fraction, and mass balance
HydrogenPlantBuilderTest Runnable SMR, ATR, POX, and full blue-H₂ plant builder templates
HydrogenProductionBenchmarkTest Benchmark envelopes for SMR, ATR, POX, PSA/capture, full blue-H2 chain, and carbon-intensity metrics

Deferred to Horizon 2 / 3