Physics-Based Risk Integration in NeqSim

This document describes how the risk framework integrates with NeqSim’s physics-based process simulation capabilities.

Overview

The risk framework now provides two levels of integration with NeqSim:

  1. Basic Integration - Uses ProcessSystem for equipment lists and baseline production
  2. Physics-Based Integration - Directly reads T, P, capacity utilization from equipment

Key Classes

ProcessEquipmentMonitor (Physics-Based)

The ProcessEquipmentMonitor class directly connects to NeqSim equipment to:

// Create monitor for a separator
ProcessEquipmentMonitor monitor = new ProcessEquipmentMonitor(separator);
monitor.setDesignTemperatureRange(273.15, 373.15); // K
monitor.setDesignPressureRange(1.0, 100.0);        // bara
monitor.setBaseFailureRate(0.0001);                // per hour

// After process runs, update reads from equipment
process.run();
monitor.update();

// Health and failure rate based on physics
double health = monitor.getHealthIndex();        // 0-1
double failRate = monitor.getAdjustedFailureRate(); // increases if outside design range
double prob24h = monitor.getFailureProbability(24); // 24-hour failure probability

PhysicsBasedRiskMonitor

Performs system-wide risk assessment using NeqSim’s physics:

PhysicsBasedRiskMonitor riskMonitor = new PhysicsBasedRiskMonitor(processSystem);

// Configure design limits
riskMonitor.setDesignTemperatureRange("HP Separator", 273.15, 373.15);
riskMonitor.setDesignPressureRange("HP Separator", 1.0, 100.0);
riskMonitor.setBaseFailureRate("Compressor1", 0.0001);

// Run assessment
PhysicsBasedRiskAssessment assessment = riskMonitor.assess();

// Results derived from physics
System.out.println("Overall Risk: " + assessment.getOverallRiskScore());
System.out.println("Bottleneck: " + assessment.getBottleneckEquipment());
System.out.println("System Margin: " + assessment.getSystemCapacityMargin());

How Risk Scores Are Calculated

The physics-based risk calculation considers:

1. Equipment Health Index

Based on deviation from design conditions:

Condition Health Index
Within design range 0.8 - 1.0
Near design limits 0.5 - 0.8
Outside design range < 0.5

2. Adjusted Failure Rate

adjustedFailureRate = baseFailureRate × exp((1 - healthIndex) × 3)

Low health → exponentially higher failure rate

3. Capacity-Weighted Consequence

Equipment at high utilization has higher consequence:

consequenceWeight = 1 + utilization × 2  (ranges 1x to 3x)

Bottleneck equipment has 2x additional weight.

4. Overall Risk Score

overallRisk = capacityRisk + healthRisk + maxEquipmentRisk

Where:

NeqSim APIs Used

NeqSim API Risk Usage
processSystem.findBottleneck() Identify system-limiting equipment
processSystem.getCapacityUtilizationSummary() Get all equipment utilizations
processSystem.getConstrainedEquipment() List equipment with capacity tracking
equipment.getTemperature() Condition monitoring
equipment.getPressure() Condition monitoring
CapacityConstrainedEquipment.getMaxUtilization() Capacity-based risk
CapacityConstrainedEquipment.getBottleneckConstraint() Constraint identification

Example: Complete Physics-Based Risk Assessment

// Build process
SystemInterface gas = new SystemSrkEos(273.15 + 40, 80.0);
gas.addComponent("methane", 0.85);
gas.addComponent("ethane", 0.10);
gas.addComponent("propane", 0.05);
gas.setMixingRule("classic");

Stream feed = new Stream("Feed", gas);
feed.setFlowRate(10000, "kg/hr");

ThrottlingValve valve = new ThrottlingValve("Inlet Valve", feed);
valve.setOutletPressure(40.0, "bara");

Separator separator = new Separator("HP Separator", valve.getOutletStream());

ProcessSystem process = new ProcessSystem();
process.add(feed);
process.add(valve);
process.add(separator);
process.run();

// Create physics-based risk monitor
PhysicsBasedRiskMonitor riskMonitor = new PhysicsBasedRiskMonitor(process);

// Set design envelopes
riskMonitor.setDesignTemperatureRange("HP Separator", 273.15, 373.15);
riskMonitor.setDesignPressureRange("HP Separator", 1.0, 100.0);
riskMonitor.setBaseFailureRate("HP Separator", 0.0001);

// Get assessment
PhysicsBasedRiskAssessment assessment = riskMonitor.assess();

// Output physics-based results
System.out.println("=== Physics-Based Risk Assessment ===");
System.out.println("Overall Risk Score: " + assessment.getOverallRiskScore());
System.out.println("System Capacity Margin: " + assessment.getSystemCapacityMargin());
System.out.println("Bottleneck: " + assessment.getBottleneckEquipment());
System.out.println("\nEquipment Health:");
for (Map.Entry<String, Double> e : assessment.getEquipmentHealthIndices().entrySet()) {
    System.out.println("  " + e.getKey() + ": " + String.format("%.2f", e.getValue()));
}
System.out.println("\nEquipment Risk Scores:");
for (Map.Entry<String, Double> e : assessment.getEquipmentRiskScores().entrySet()) {
    System.out.println("  " + e.getKey() + ": " + String.format("%.3f", e.getValue()));
}

Comparison: Basic vs Physics-Based

Feature Basic (OperationalRiskSimulator) Physics-Based (PhysicsBasedRiskMonitor)
Temperature monitoring Manual input Auto from equipment
Pressure monitoring Manual input Auto from equipment
Capacity utilization Not used From CapacityConstrainedEquipment
Bottleneck detection Not used Uses ProcessSystem.findBottleneck()
Health calculation N/A Based on T/P deviation from design
Failure rate Fixed per equipment Dynamic based on conditions

Best Practices

  1. Use PhysicsBasedRiskMonitor when process conditions vary
  2. Set realistic design limits - these define the “normal operating envelope”
  3. Run process.run() before assessment to ensure current physics values
  4. Check warnings in assessment for equipment near limits
  5. Monitor capacity margin - values < 0.1 indicate system near limits