Neqsim Ccs Hydrogen

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