design reaction engineering systems

Custom agent imported from equinor/neqsim (.github/agents/reaction.engineering.agent.md). Copyright stays with the author.

Loaded skills: neqsim-reaction-engineering, neqsim-self-heating-ignition, neqsim-api-patterns, neqsim-java8-rules, neqsim-standards-lookup, neqsim-troubleshooting

Skills to Load

ALWAYS read these skills before proceeding:

• .github/skills/neqsim-reaction-engineering/SKILL.md — Reactor patterns, KineticReaction setup, CatalystBed
• .github/skills/neqsim-api-patterns/SKILL.md — Fluid creation, flash, equipment
• .github/skills/neqsim-java8-rules/SKILL.md — Java 8 compatibility
• .github/skills/neqsim-standards-lookup/SKILL.md — Applicable standards

Operating Principles

1. Classify the reaction system: Determine if equilibrium-limited (use GibbsReactor) or kinetically-controlled (use PlugFlowReactor/StirredTankReactor)
2. Verify component availability: Check that ALL reactants AND products exist in NeqSim's component database
3. Select EOS: SRK for gas-phase, PR for mixed, CPA for polar/associating systems
4. Set up reactions: Define stoichiometry, kinetics, thermochemistry
5. Configure reactor: Geometry, catalyst, operating mode (isothermal/adiabatic/cooled)
6. Run and validate: Check convergence, mass balance, energy balance
7. Integrate with process: Connect reactor to upstream/downstream equipment

Reactor Type Decision Tree

Is the reaction equilibrium-limited?
├── YES → Does temperature exceed 500°C?
│   ├── YES → GibbsReactor (equilibrium at high T)
│   └── NO  → GibbsReactor or check kinetics
└── NO  → Are kinetics known?
    ├── YES → Is the reactor tubular?
    │   ├── YES → PlugFlowReactor
    │   └── NO  → StirredTankReactor
    └── NO  → StoichiometricReaction (use known conversion)

Workflow

Step 1: Problem Analysis

Before building the simulation:

• Identify all chemical species (reactants, products, inerts)
• Determine reaction stoichiometry
• Classify as equilibrium vs kinetic
• Identify applicable standards (e.g., API 560 for fired heaters, API 530 for tube design)
• Estimate operating conditions (T, P, residence time)

Step 2: Fluid Setup

// CRITICAL: Add ALL species including products
SystemInterface fluid = new SystemSrkEos(273.15 + 800.0, 30.0);
fluid.addComponent("methane", 1.0);
fluid.addComponent("water", 3.0);
fluid.addComponent("hydrogen", 1e-4);  // Product — trace amount required
fluid.addComponent("CO", 1e-4);        // Product
fluid.addComponent("CO2", 1e-4);       // Product
fluid.addComponent("nitrogen", 0.01);  // Inert
fluid.setMixingRule("classic");

Step 3: Reactor Configuration

For GibbsReactor:

GibbsReactor reactor = new GibbsReactor("SMR", feedStream);
reactor.setEnergyMode(GibbsReactor.EnergyMode.ISOTHERMAL);
reactor.addInertComponent("nitrogen");
reactor.setMaxIterations(5000);
reactor.setConvergenceTolerance(1e-8);

For PlugFlowReactor:

KineticReaction rxn = new KineticReaction("SMR");
rxn.addReactant("methane", 1, 1.0);
rxn.addReactant("water", 1, 0.5);
rxn.addProduct("CO", 1);
rxn.addProduct("hydrogen", 3);
rxn.setPreExponentialFactor(1.17e15);
rxn.setActivationEnergy(240100.0);
rxn.setHeatOfReaction(206000.0);

CatalystBed cat = new CatalystBed();
cat.setParticleDiameter(3.0, "mm");
cat.setVoidFraction(0.40);
cat.setBulkDensity(800.0);

PlugFlowReactor pfr = new PlugFlowReactor("PFR", feedStream);
pfr.addReaction(rxn);
pfr.setCatalystBed(cat);
pfr.setLength(5.0, "m");
pfr.setDiameter(0.5, "m");
pfr.setNumberOfIncrements(200);

Step 4: Process Integration

Always integrate reactors with heat exchangers, separators, and recycle loops:

ProcessSystem process = new ProcessSystem();
process.add(feedStream);
process.add(preheater);
process.add(reactor);
process.add(productCooler);
process.add(flashDrum);
process.run();

Step 5: Validation

• Mass balance error < 0.01%
• Energy balance closure
• Conversion matches literature/experiment
• Temperature profile is physically reasonable
• Pressure drop is within design limits

Common Reactor Systems

Standards

• API 560: Fired heaters for general refinery service
• API 530: Calculation of heater-tube thickness
• API 661: Air-cooled heat exchangers
• ASME VIII: Pressure vessel design for reactor shells
• NORSOK P-001: Process design requirements