DensePhaseCO2Corrosion

Package: neqsim.process.corrosion

Standards: DNV-RP-J202, ISO 27913, DNV-RP-F104, ASME B31.4

Evaluates corrosion risk in dense-phase CO2 transport systems for carbon capture and storage (CCS). In dry dense-phase CO2, corrosion is negligible — but free water formation from impurity interactions can cause severe attack exceeding 10 mm/yr.

Key Principle

Dense-phase CO2 is only corrosive when free water forms. The critical assessment is whether the actual water content exceeds the water solubility limit at the operating conditions:

\[\text{Water margin} = \text{Solubility limit} - \text{Actual water content}\]

Negative margin = free water risk = potential for severe corrosion.

Impurity Specification Limits

Impurity Typical Spec Limit Risk
H2O 50–500 ppmv Free water formation → corrosion
O2 10–100 ppmv Acidification with SO2/NOx
SO2 10–50 ppmv Sulfurous acid formation
NOx 10–50 ppmv Nitric acid formation
H2S 50–200 ppmv Sour corrosion if water present
H2 < 2 mol% Material embrittlement

Quick Start

Java

import neqsim.process.corrosion.DensePhaseCO2Corrosion;

DensePhaseCO2Corrosion co2 = new DensePhaseCO2Corrosion();
co2.setTemperatureC(25.0);
co2.setPressureBara(110.0);
co2.setCo2PurityMolPct(98.5);
co2.setWaterContentPpmv(200.0);
co2.setO2ContentPpmv(50.0);
co2.setSo2ContentPpmv(20.0);
co2.setNoxContentPpmv(10.0);
co2.setH2sContentPpmv(100.0);
co2.setH2ContentMolPct(0.5);
co2.setMaterialType("Carbon steel");
co2.evaluate();

System.out.println("Free Water Risk: " + co2.isFreeWaterRisk());
System.out.println("Water Margin: " + co2.getWaterMarginPpmv() + " ppmv");
System.out.println("Risk Level: " + co2.getRiskLevel());
System.out.println("Wet Corrosion Rate: " + co2.getWetCorrosionRateMmYr() + " mm/yr");
System.out.println("Meets Specs: " + co2.isMeetsImpuritySpecs());
System.out.println("Phase: " + co2.getCo2PhaseState());
System.out.println("Recommendation: " + co2.getRecommendation());

Python

from neqsim import jneqsim

DenseCO2 = jneqsim.process.corrosion.DensePhaseCO2Corrosion

co2 = DenseCO2()
co2.setTemperatureC(25.0)
co2.setPressureBara(110.0)
co2.setCo2PurityMolPct(98.5)
co2.setWaterContentPpmv(200.0)
co2.setO2ContentPpmv(50.0)
co2.setSo2ContentPpmv(20.0)
co2.evaluate()

print(f"Free water risk: {co2.isFreeWaterRisk()}")
print(f"Risk level: {co2.getRiskLevel()}")
print(f"Phase: {co2.getCo2PhaseState()}")

Integration with NeqSim Fluid

// Auto-extract impurity levels from a NeqSim fluid
DensePhaseCO2Corrosion co2 = new DensePhaseCO2Corrosion();
co2.setFluid(flashedCO2System);  // auto-reads compositions
co2.evaluate();

Input Parameters

Method Type Default Description
setTemperatureC(double) double 25.0 Temperature (°C)
setPressureBara(double) double 100.0 Pressure (bara)
setCo2PurityMolPct(double) double 99.0 CO2 purity (mol%)
setWaterContentPpmv(double) double 0.0 Water content (ppmv)
setO2ContentPpmv(double) double 0.0 O2 content (ppmv)
setSo2ContentPpmv(double) double 0.0 SO2 content (ppmv)
setNoxContentPpmv(double) double 0.0 NOx content (ppmv)
setH2sContentPpmv(double) double 0.0 H2S content (ppmv)
setH2ContentMolPct(double) double 0.0 H2 content (mol%)
setN2ContentMolPct(double) double 0.0 N2 content (mol%)
setArContentMolPct(double) double 0.0 Ar content (mol%)
setMaterialType(String) String “Carbon steel” Material type
setFluid(SystemInterface) SystemInterface — Auto-extract compositions from fluid

Output Methods

Method Return Type Description
isFreeWaterRisk() boolean Whether free water may form
getWaterSolubilityLimitPpmv() double Water solubility limit at conditions (ppmv)
getWaterMarginPpmv() double Margin below solubility limit (negative = risk)
getRiskLevel() String “Low”, “Medium”, “High”, “Very High”
getWetCorrosionRateMmYr() double Estimated corrosion rate if water present (mm/yr)
isMeetsImpuritySpecs() boolean Whether all impurities are within spec
getImpurityIssues() List<String> List of impurity limit exceedances
getCo2PhaseState() String “Gas”, “Liquid”, “Supercritical”, “Dense phase”
getRecommendation() String Corrosion management recommendation
getNotes() List<String> Assessment notes
toMap() Map All results as a LinkedHashMap
toJson() String Complete JSON report