neqsim-relief-flare-network

NeqSim Relief & Flare Network Skill

End-to-end relief design — from individual PSV sizing through plant-wide load summation, flare-tip selection, and radiation/dispersion checks per API 520, API 521, API 537.

When to Use

• Sizing a single PSV (gas / liquid / two-phase / fire case)
• Checking whether a blocked-in liquid segment needs thermal relief or source-term handoff after rupture screening
• API 521 fire heat input on wetted area
• Aggregating simultaneous relief loads to a flare header
• Flare tip diameter and stack height (radiation)
• Header hydraulics: back-pressure on PSVs, Mach < 0.7
• Sour-gas dispersion check (toxic clouds)

Standards: API 520 Part I/II, API 521 (relief contingencies + radiation), API 537 (flare equipment), NFPA 30, EN ISO 23251.

Pattern 1 — Gas-phase PSV (API 520)

import neqsim.process.util.fire.ReliefValveSizing;
import neqsim.process.util.fire.ReliefValveSizing.PSVSizingResult;

PSVSizingResult psv = ReliefValveSizing.calculateRequiredArea(
    massFlowRate_kgs,
    setPressure_barg,
    backPressure_barg,
    T_K,
    MW,
    k_cpcv,            // ratio of specific heats
    Z_compressibility,
    overpressure_frac, // 0.10 process, 0.21 fire
    Kd                 // discharge coeff (0.975 typical)
);

double area_m2  = psv.getRequiredArea();
String orifice  = psv.getRecommendedOrifice();        // API 526 letter
String issues   = ReliefValveSizing.validateSizing(psv, /*fire*/ false);

Pattern 2 — Fire Case (API 521)

double Q_fire_W = ReliefValveSizing.calculateAPI521FireHeatInput(
    wettedAreaM2,
    /*hasDrainage*/ true,
    /*hasFireProofInsulation*/ false
);

// Mass flow = Q_fire / latent heat at relieving conditions
double mdot = Q_fire_W / latentHeat_J_per_kg;

PSVSizingResult psv = ReliefValveSizing.calculateRequiredArea(
    mdot, setP, backP, T_relief, MW, k, Z,
    /*overpressure_frac*/ 0.21,   // fire allows 21%
    Kd
);

API 521 fire equation: Q = C × F × A_wet^0.82 with credit factors for drainage / insulation.