LPG Bulk Import Terminal, Single Buoy Mooring (SBM), Horton-Sphere Storage & Bridger Gantry Dispatch ERP: Custody-Transfer Coriolis Metering, Vapor-Return Mass Balance, KRA Customs Bonded Outturn & Gantry Loading

Bulk Liquefied Petroleum Gas (LPG) marine import terminals, pressurized spherical Horton-sphere and mounded bullet tank farms, and hospitality/hospitality-hospitality wholesale bridger loading gantries in Mombasa (Kipevu, Shimanzi, Changamwe), Nairobi, Eldoret, Kisumu, and Dar es Salaam handle volatile pressurized hydrocarbon mixtures (commercial propane-butane ratios) where temperature, vapor pressure, and liquid-vapor phase equilibrium directly alter measured mass. Managing marine tanker outturns, third-party hospitality/hospitality storage hospitality agreements, KRA Customs bonded entries, and road bridger gantry loading on spreadsheets leads to unexplained vapor-phase mass losses, disputes between ship Bill of Lading figures and shore sphere receipts, customs bond overruns, and loading-bay queue bottlenecks.

At devManue, we engineer industrial-grade Bulk LPG Import Terminal, Spherical Tank Farm & Gantry Dispatch ERP platforms. Our system integrates radar/servo tank gauging, Coriolis mass-flow meters, ASTM D1250 / API MPMS Table 53E & 54E liquid-and-vapor density conversions at 15°C, KRA iCMS bonded warehouse stock ledgers, and automated PLC weighbridge/mass-meter bridger loading bays.

1. Marine LPG Vessel Outturn, Coriolis Mass-Flow & Liquid + Vapor Sphere Mass-Balance

Unlike atmospheric liquid fuels, an LPG storage sphere or mounded bullet contains both a pressurized liquid phase at the bottom and a compressed hydrocarbon vapor phase in the head-space above the liquid level. Ignoring the mass of the vapor phase—or failing to compensate for vapor-return lines during vessel discharge and bridger loading—creates false stock gains or losses of several metric tonnes per sphere.

• Marine Tanker Discharge & Custody-Transfer Coriolis Metering: Logs ship figure vs. shore Coriolis mass-flow meter readings, pipeline packing state, pigging operations, and propane:butane GC composition ratios (e.g., 30:70 or 20:80 C3:C4) to generate the official Shore Outturn Report.
• Dual-Phase (Liquid + Vapor) Spherical Tank Gauging at 15°C: Interfaces with high-precision radar level gauges, multi-spot temperature elements, and top/bottom pressure transmitters to compute true liquid volume, liquid mass at 15°C, head-space vapor volume, and compressed vapor mass inside every Horton sphere and mounded bullet.
• Third-Party Hospitality & Common-User Terminal Commingled Accounting: Tracks individual Oil Marketing Company (OMC) stock entitlements, marine discharge hospitality fees, pipeline throughput tariffs, and contractual handling loss allowances (e.g., 0.25%).

2. Dual-Phase (Liquid + Vapor) LPG Sphere Mass & Bridger Gantry Outturn Engine

Our terminal mass-balance engine calculates the exact combined liquid and vapor metric tonnage inside a pressurized storage vessel and reconciles sphere depletion against road/rail bridger weighbridge and Coriolis gantry outturns:

from decimal import Decimal, ROUND_HALF_UP

class LpgTerminalDualPhaseMassBalanceEngine:
    """
    Computes total LPG mass (Metric Tonnes) across both liquid phase and
    pressurized head-space vapor phase inside a Horton Sphere or Mounded Bullet,
    and audits gantry bridger dispatch variance.
    """
    @staticmethod
    def calculate_sphere_dual_phase_mass_and_variance(
        total_sphere_capacity_m3: Decimal,
        observed_liquid_volume_m3: Decimal,
        vcf_table_54e_at_15c: Decimal,
        density_at_15c_kg_per_m3: Decimal,
        sphere_vapor_pressure_bar_abs: Decimal,
        vapor_temperature_celsius: Decimal,
        molecular_weight_kg_per_kmol: Decimal,  # e.g. ~53.8 for 30:70 Propane/Butane
        opening_sphere_mass_mt: Decimal,
        gantry_bridger_dispatches_mt: Decimal,
    ) -> dict:
        # 1. Liquid phase mass at 15°C (vacuum/air-buoyancy corrected)
        standard_liquid_vol_15c_m3 = (
            observed_liquid_volume_m3 * vcf_table_54e_at_15c
        ).quantize(Decimal("0.001"), rounding=ROUND_HALF_UP)
        liquid_mass_mt = (
            (standard_liquid_vol_15c_m3 * density_at_15c_kg_per_m3) / Decimal("1000.0")
        ).quantize(Decimal("0.001"), rounding=ROUND_HALF_UP)

        # 2. Head-space compressed vapor phase mass via real-gas compressibility approximation
        vapor_space_volume_m3 = max(Decimal("0.0"), total_sphere_capacity_m3 - observed_liquid_volume_m3)
        temp_kelvin = vapor_temperature_celsius + Decimal("273.15")
        gas_constant_r = Decimal("0.08314")  # bar·m3 / (kmol·K)
        compressibility_z = Decimal("0.88")  # typical LPG vapor compressibility factor
        vapor_density_kg_m3 = (
            (sphere_vapor_pressure_bar_abs * molecular_weight_kg_per_kmol)
            / (compressibility_z * gas_constant_r * temp_kelvin)
        )
        vapor_mass_mt = (
            (vapor_space_volume_m3 * vapor_density_kg_m3) / Decimal("1000.0")
        ).quantize(Decimal("0.001"), rounding=ROUND_HALF_UP)

        closing_total_sphere_mass_mt = (liquid_mass_mt + vapor_mass_mt).quantize(
            Decimal("0.001"), rounding=ROUND_HALF_UP
        )
        sphere_depletion_mt = (opening_sphere_mass_mt - closing_total_sphere_mass_mt).quantize(
            Decimal("0.001"), rounding=ROUND_HALF_UP
        )
        mass_variance_mt = (gantry_bridger_dispatches_mt - sphere_depletion_mt).quantize(
            Decimal("0.001"), rounding=ROUND_HALF_UP
        )

        return {
            "liquid_phase_mass_mt": liquid_mass_mt,
            "vapor_headspace_mass_mt": vapor_mass_mt,
            "closing_total_sphere_mass_mt": closing_total_sphere_mass_mt,
            "sphere_mass_depletion_mt": sphere_depletion_mt,
            "gantry_vs_sphere_variance_mt": mass_variance_mt,
            "reconciliation_status": "WITHIN_0.2_PCT_CUSTODY_TOLERANCE" if abs(mass_variance_mt) <= Decimal("0.500") else "AUDIT_VAPOR_RETURN_OR_METER",
        }

3. Automated Bridger Gantry Loading, Ethyl Mercaptan Odorizing & EPRA Safety Interlocks

At the road and rail bridger loading gantry, our ERP enforces zero-compromise process safety and tax compliance before a single kilogram of LPG is pumped:

• EPRA Licensing, Pressure-Vessel Hydro-Test & Grounding Interlocks: Blocks loading order release if the road bridger’s EPRA Bulk LPG Transport Permit, 5-year statutory pressure-vessel hydro-test certificate, relief-valve calibration, or driver Hazmat license has expired.
• Maximum Safe Fill (85% Ullage Ceiling) & Odorant Dosing Logs: Calculates the maximum permissible net LPG load based on the tanker’s water capacity and product specific gravity so liquid fill never exceeds 85% volume (leaving 15% thermal expansion ullage), and logs ethyl mercaptan stench dosing per metric tonne.
• Dual Weighbridge + Coriolis Gantry Cutoff & KRA Customs Release: Cross-checks gantry Coriolis mass-meter delivery against inbound Tare and outbound Gross weighbridge tickets, deducts the exact tonnage from the OMC’s duty-paid KRA Customs release order, and prints the Bill of Lading, CoA, and eTIMS invoice.