Neqsim Ccs Hydrogen

CCS and Hydrogen Systems with NeqSim

Guide for modeling carbon capture and storage (CCS) value chains and hydrogen systems, including CO2 transport, injection wells, impurity effects, and H2 blending.

When to Use This Skill

• CO2 pipeline design and phase behavior
• CO2 injection well analysis and safety
• Impurity effects on CO2 phase envelope (H2, N2, O2, H2S, CH4)
• Dense phase CO2 transport conditions
• CO2 dehydration requirements
• Hydrogen blending with natural gas
• Water electrolysis and green hydrogen
• Blue hydrogen (SMR/ATR + CCS)
• Hydrogen pipeline transport

Applicable Standards

1. CO2 Phase Behavior

CO2 Critical Point and Phase Envelope

CO2 critical point: 31.1°C, 73.8 bara. Most CO2 pipelines operate in dense phase (above critical pressure) to avoid two-phase flow.

// Pure CO2 phase behavior
SystemInterface co2 = new SystemSrkEos(273.15 + 25, 80.0);
co2.addComponent("CO2", 1.0);
co2.setMixingRule("classic");

ThermodynamicOperations ops = new ThermodynamicOperations(co2);
ops.calcPTphaseEnvelope();
// CO2 is in dense/supercritical phase at typical pipeline conditions (>80 bara, 4-40°C)

Impurity Effects on CO2 Phase Envelope

Impurities widen the phase envelope and raise the cricondenbar, creating risk of two-phase flow in pipelines designed for dense phase operation.

// CO2 with typical impurities from post-combustion capture
SystemInterface co2Mix = new SystemSrkEos(273.15 + 10, 110.0);
co2Mix.addComponent("CO2", 0.95);
co2Mix.addComponent("nitrogen", 0.02);
co2Mix.addComponent("oxygen", 0.005);
co2Mix.addComponent("water", 0.005);
co2Mix.addComponent("H2S", 0.001);
co2Mix.addComponent("hydrogen", 0.005);
co2Mix.addComponent("methane", 0.014);
co2Mix.setMixingRule("classic");
co2Mix.setMultiPhaseCheck(true);

ThermodynamicOperations ops = new ThermodynamicOperations(co2Mix);
ops.calcPTphaseEnvelope();
// Compare cricondenbar with pure CO2 — impurities raise it significantly
// N2, H2, O2 have the largest effect on raising cricondenbar

Impurity Impact Ranking (on phase envelope)

2. CO2 Pipeline Design

Dense Phase Transport

// Typical CO2 pipeline: 110 bara inlet, 80 bara min, 4-40°C
Stream co2Feed = new Stream("CO2 Feed", co2Mix);
co2Feed.setFlowRate(1000000.0, "kg/hr");  // ~1 Mt/yr
co2Feed.setTemperature(25.0, "C");
co2Feed.setPressure(110.0, "bara");

PipeBeggsAndBrills pipeline = new PipeBeggsAndBrills("CO2 Pipeline", co2Feed);
pipeline.setLength(150000.0);     // 150 km
pipeline.setDiameter(0.508);       // 20 inch
pipeline.setPipeWallRoughness(5e-5);
pipeline.setOuterTemperature(277.15);  // 4°C seabed
pipeline.run();

double outP = pipeline.getOutletStream().getPressure();
double outT = pipeline.getOutletStream().getTemperature() - 273.15;
// Verify: outlet P > cricondenbar to stay in dense phase

CO2 Dehydration Requirement

// Water content must be below ~50 ppmv to prevent hydrate and corrosion
// Use CPA for accurate water in CO2 modeling
SystemInterface wetCO2 = new SystemSrkCPAstatoil(273.15 + 25, 110.0);
wetCO2.addComponent("CO2", 0.99);
wetCO2.addComponent("water", 0.01);
wetCO2.setMixingRule(10);
wetCO2.setMultiPhaseCheck(true);

ThermodynamicOperations ops = new ThermodynamicOperations(wetCO2);
ops.TPflash();
wetCO2.initProperties();

// Check water content in CO2-rich phase
double waterInCO2 = wetCO2.getPhase("gas").getComponent("water").getx();
// Convert to ppmv and compare with spec (typically <50 ppmv)

3. CO2 Injection Well Analysis

Full-Stack Well Analysis

CO2InjectionWellAnalyzer analyzer = new CO2InjectionWellAnalyzer("InjWell-1");
analyzer.setFluid(co2Fluid);
analyzer.setWellGeometry(1300.0, 0.1571, 5e-5);  // depth, ID, roughness
analyzer.setOperatingConditions(90.0, 25.0, 150000.0);  // P, T, flow
analyzer.setFormationTemperature(4.0, 43.0);  // surface T, bottomhole T
analyzer.addTrackedComponent("hydrogen", 0.10);  // impurity limit
analyzer.runFullAnalysis();

boolean safe = analyzer.isSafeToOperate();
// Checks: phase transitions in wellbore, impurity enrichment, thermal stress

Wellbore Temperature Profile

PipeBeggsAndBrills wellbore = new PipeBeggsAndBrills("CO2 Injector", co2Feed);
wellbore.setLength(1300.0);
wellbore.setElevation(-1300.0);  // vertical injection well
wellbore.setDiameter(0.1571);     // 6-5/8 inch tubing
wellbore.setPipeWallRoughness(5e-5);
wellbore.setFormationTemperatureGradient(4.0, -0.03, "C");
wellbore.run();

double bhp = wellbore.getOutletStream().getPressure();
double bht = wellbore.getOutletStream().getTemperature() - 273.15;

Impurity Enrichment Monitoring

During phase transitions in the wellbore, light impurities (H2, N2) concentrate in the gas phase, potentially exceeding well material limits.

ImpurityMonitor monitor = new ImpurityMonitor("H2-Monitor", stream);
monitor.addTrackedComponent("hydrogen", 0.10);   // 10 mol% limit
monitor.addTrackedComponent("H2S", 0.001);        // 0.1% limit
monitor.addTrackedComponent("oxygen", 0.005);     // 0.5% limit

double h2Enrichment = monitor.getEnrichmentFactor("hydrogen");
boolean h2Safe = !monitor.exceedsLimit("hydrogen");

Shutdown Transient Analysis

TransientWellbore wellbore = new TransientWellbore("Shutdown", co2Feed);
wellbore.setWellDepth(1300.0);
wellbore.setFormationTemperature(277.15, 316.15);  // surface, bottom (K)
wellbore.setShutdownCoolingRate(6.0);  // °C/hr cooling rate
wellbore.runShutdownSimulation(48.0, 1.0);  // 48 hours, 1 hr timestep

// Check for phase transition during cooldown
// Risk: CO2 may transition to two-phase, causing pressure surges

CO2 Flow Corrections

// Static utility for CO2-specific flow adjustments
boolean dense = CO2FlowCorrections.isDensePhase(system);
double holdupCorr = CO2FlowCorrections.getLiquidHoldupCorrectionFactor(system);
// Dense phase CO2 requires modified correlations for pressure drop

4. Hydrogen Systems

Hydrogen Blending with Natural Gas

// Evaluate H2 blending impact on existing gas network
SystemInterface blendedGas = new SystemSrkEos(273.15 + 15, 70.0);
blendedGas.addComponent("hydrogen", 0.10);   // 10% H2 blend
blendedGas.addComponent("methane", 0.81);
blendedGas.addComponent("ethane", 0.05);
blendedGas.addComponent("propane", 0.02);
blendedGas.addComponent("nitrogen", 0.02);
blendedGas.setMixingRule("classic");

ThermodynamicOperations ops = new ThermodynamicOperations(blendedGas);
ops.TPflash();
blendedGas.initProperties();

// Key impacts of H2 blending:
double density = blendedGas.getDensity("kg/m3");       // Decreases with H2
double gcv = blendedGas.getPhase("gas").getCp("J/kgK"); // Changes energy content
double z = blendedGas.getZ();                            // Compressibility changes

// For Wobbe index and calorific value:
Standard_ISO6976 iso = new Standard_ISO6976(blendedGas);
iso.calculate();
double wobbe = iso.getValue("SuperiorWobbeIndex");
// H2 reduces Wobbe index — check against pipeline spec limits

Hydrogen Pipeline Transport

// H2 has very low density — requires higher velocities or larger diameters
Stream h2Feed = new Stream("H2 Feed", h2Fluid);
h2Feed.setFlowRate(10000.0, "kg/hr");
h2Feed.setPressure(70.0, "bara");

PipeBeggsAndBrills h2Pipe = new PipeBeggsAndBrills("H2 Pipeline", h2Feed);
h2Pipe.setLength(100000.0);   // 100 km
h2Pipe.setDiameter(0.508);     // 20 inch
h2Pipe.setPipeWallRoughness(5e-5);
h2Pipe.run();

// H2 pressure drop is lower per unit mass but energy density is much lower
// Consider: material compatibility (H2 embrittlement), safety zones

Blue Hydrogen (SMR + CCS)

// Steam Methane Reforming produces H2 + CO2
// CH4 + H2O -> CO + 3H2 (reforming)
// CO + H2O -> CO2 + H2 (water-gas shift)

// Model with GibbsReactor for equilibrium
SystemInterface syngasFluid = new SystemSrkEos(273.15 + 850, 30.0);
syngasFluid.addComponent("methane", 0.25);
syngasFluid.addComponent("water", 0.75);
syngasFluid.setMixingRule("classic");

GibbsReactor reformer = new GibbsReactor("SMR", syngasFeed);
reformer.run();
// Outlet: H2, CO, CO2, H2O, unconverted CH4

5. CCS Value Chain Integration

Capture → Transport → Storage Workflow

// 1. Post-combustion capture outlet (after amine scrubbing)
SystemInterface capturedCO2 = new SystemSrkEos(273.15 + 40, 2.0);
capturedCO2.addComponent("CO2", 0.995);
capturedCO2.addComponent("nitrogen", 0.003);
capturedCO2.addComponent("water", 0.002);
capturedCO2.setMixingRule("classic");

// 2. Compression to pipeline pressure
Stream co2Stream = new Stream("Captured CO2", capturedCO2);
co2Stream.setFlowRate(500000.0, "kg/hr");

// Multi-stage compression with intercooling
Compressor comp1 = new Compressor("Stage 1", co2Stream);
comp1.setOutletPressure(5.0);
Cooler cooler1 = new Cooler("IC 1", comp1.getOutletStream());
cooler1.setOutTemperature(273.15 + 30);

Compressor comp2 = new Compressor("Stage 2", cooler1.getOutletStream());
comp2.setOutletPressure(20.0);
Cooler cooler2 = new Cooler("IC 2", comp2.getOutletStream());
cooler2.setOutTemperature(273.15 + 30);

Compressor comp3 = new Compressor("Stage 3", cooler2.getOutletStream());
comp3.setOutletPressure(80.0);
Cooler cooler3 = new Cooler("IC 3", comp3.getOutletStream());
cooler3.setOutTemperature(273.15 + 30);

// 3. Pump to pipeline pressure (above critical — dense phase)
// CO2 is liquid above ~65 bara at 30°C, pump is more efficient than compressor
Compressor pump = new Compressor("Pump", cooler3.getOutletStream());
pump.setOutletPressure(150.0);

// 4. Pipeline transport
PipeBeggsAndBrills pipeline = new PipeBeggsAndBrills("CO2 Export", pump.getOutletStream());
pipeline.setLength(200000.0);  // 200 km
pipeline.setDiameter(0.508);
pipeline.setOuterTemperature(277.15);

// 5. Injection well
// See CO2InjectionWellAnalyzer above

ProcessSystem ccsProcess = new ProcessSystem();
ccsProcess.add(co2Stream);
ccsProcess.add(comp1); ccsProcess.add(cooler1);
ccsProcess.add(comp2); ccsProcess.add(cooler2);
ccsProcess.add(comp3); ccsProcess.add(cooler3);
ccsProcess.add(pump);
ccsProcess.add(pipeline);
ccsProcess.run();

double totalPower = comp1.getPower("kW") + comp2.getPower("kW")
                  + comp3.getPower("kW") + pump.getPower("kW");

6. Common Pitfalls